642
domain: N
Properties
Digital Properties
- Digit Count
- 3
- Digit Sum
- 12
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 1296
- Proper Divisor Sum (Aliquot Sum)
- 654
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- yes
Derived Values
- Euler's Totient
- 212
- Möbius Function
- -1
- Radical
- 642
- Omega Function (Ω)
- 3
- Little Omega Function (ω)
- 3
Special
- Factorial
- no
- Catalan Number
- no
- Bell Number
- no
- Motzkin Number
- no
- Primorial
- no
Figurate Numbers
- Fibonacci Number
- no
- Triangular Number
- no
- Perfect Square
- no
- Perfect Cube
- no
- Pentagonal Number
- no
- Hexagonal Number
- no
- Lucas Number
- no
- Tetrahedral Number
- no
- Pell Number
- no
- Tribonacci Number
- no
- Pronic Number
- no
Recreational
- Happy Number
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 25
- Smith Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- yes
- Prime Power
- no
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- yes
- Odd
- no
Names
- German
- sechshundertzweiundvierzig· ordinal: sechshundertzweiundvierzigste
- English
- six hundred forty-two· ordinal: six hundred forty-second
- Spanish
- seiscientos cuarenta y dos· ordinal: 642º
- French
- six cent quarante-deux· ordinal: six cent quarante-deuxième
- Italian
- seicentoquarantadue· ordinal: 642º
- Latin
- sescenti quadraginta duo· ordinal: 642.
- Portuguese
- seiscentos e quarenta e dois· ordinal: 642º
Appears in sequences
- Number of nonnegative solutions to x^2 + y^2 <= n^2.at n=28A000603
- Squares written in base 7.at n=17A002440
- Denominators of Bernoulli numbers B_{2n}.at n=53A002445
- Number of partitions of n into Fibonacci parts (with a single type of 1).at n=32A003107
- Numbers which are the sum of 3 nonzero 4th powers.at n=20A003337
- Numbers that are the sum of 12 positive 6th powers.at n=10A003368
- Numbers that are the sum of 7 positive 7th powers.at n=5A003374
- Sums of distinct nonzero 4th powers.at n=18A003999
- Numbers that are the sum of at most 3 nonzero 4th powers.at n=38A004832
- Numbers that are the sum of at most 4 nonzero 4th powers.at n=68A004833
- Numbers that are the sum of at most 7 positive 7th powers.at n=32A004869
- Numbers that are the sum of at most 8 positive 7th powers.at n=37A004870
- Numbers that are the sum of at most 9 positive 7th powers.at n=42A004871
- Numbers that are the sum of at most 10 positive 7th powers.at n=47A004872
- Numbers that are the sum of at most 11 positive 7th powers.at n=52A004873
- Number of points on surface of cuboctahedron (or icosahedron): a(0) = 1; for n > 0, a(n) = 10n^2 + 2. Also coordination sequence for f.c.c. or A_3 or D_3 lattice.at n=8A005901
- Numbers k such that k^16 + 1 is prime.at n=29A006313
- Numbers whose sum of divisors is a square.at n=29A006532
- Minimum diameter of an integral set of n points in the plane, not all on a line.at n=34A007285
- Shifts left when inverse Moebius transform applied twice.at n=21A007557