621
domain: N
Properties
Digital Properties
- Digit Count
- 3
- Digit Sum
- 9
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 960
- Proper Divisor Sum (Aliquot Sum)
- 339
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 396
- Möbius Function
- 0
- Radical
- 69
- Omega Function (Ω)
- 4
- Little Omega Function (ω)
- 2
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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 87
- Smith Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- 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
- no
- Odd
- yes
Names
- German
- sechshunderteinundzwanzig· ordinal: sechshunderteinundzwanzigste
- English
- six hundred twenty-one· ordinal: six hundred twenty-first
- Spanish
- seiscientos veintiuno· ordinal: 621º
- French
- six cent vingt et un· ordinal: six cent vingt et unième
- Italian
- seicentoventuno· ordinal: 621º
- Latin
- sescenti viginti unus· ordinal: 621.
- Portuguese
- seiscentos e vinte e um· ordinal: 621º
Appears in sequences
- Expansion of (Product_{j>=1} (1-(-x)^j) - 1)^6 in powers of x.at n=36A001484
- a(n) = floor(sqrt( 2*Pi )^n).at n=7A001674
- Number of integral points in a certain sequence of open quadrilaterals.at n=39A002578
- a(2*n) = floor( 17*2^n/14 ), a(2*n+1) = floor( 12*2^n/7 ).at n=18A003143
- Add 4, then reverse digits; start with 0.at n=45A003608
- Even numbers written backwards.at n=63A004093
- Number of inequivalent ways to color vertices of a regular tetrahedron using <= n colors.at n=9A006008
- Discriminants of totally real cubic fields.at n=14A006832
- Number of strict first-order maximal independent sets in cycle graph.at n=22A007391
- Some permutation of digits is a cube.at n=30A007939
- Noncubes such that some permutation of digits is a cube.at n=22A007940
- Some nontrivial permutation of digits is a cube.at n=25A007941
- Generated by a sieve: keep first number, drop every 2nd, keep first, drop every 3rd, keep first, drop every 4th, etc.at n=43A007952
- a(n) is the largest odd number k such that 9, 11, ..., k are sums of 3 of first n odd primes.at n=46A007962
- Coordination sequence T1 for Zeolite Code KFI.at n=19A008123
- Coordination sequence T6 for Zeolite Code MEL.at n=16A008155
- Coordination sequence T6 for Zeolite Code MFI.at n=16A008169
- Coordination sequence T4 for Zeolite Code MOR.at n=16A008185
- Coordination sequence T2 for Zeolite Code MTW.at n=16A008197
- Coordination sequence T3 for Zeolite Code NES.at n=16A008207