91

domain: N

Properties

Digital Properties

Digit Count
2
Digit Sum
10
Digital Root
1
Palindromic Number
no
Repdigit
no
Automorphic
no
Kaprekar Number
no
Multiplicative Persistence
1

Divisibility

Divisor Count
4
Divisor Sum
112
Proper Divisor Sum (Aliquot Sum)
21
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
72
Möbius Function
1
Radical
91
Omega Function (Ω)
2
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
yes
Perfect Square
no
Perfect Cube
no
Pentagonal Number
no
Hexagonal Number
yes
Lucas Number
no
Tetrahedral Number
no
Pell Number
no
Tribonacci Number
no
Pronic Number
no

Recreational

Happy Number
yes
Harshad Number
no
Narcissistic Number
no
Collatz Steps
92
Smith Number
no

Classification

Natural
yes
Even
no
Odd
yes

Primality

Prime
no
Composite Number
yes
Semiprime
yes
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

Names

German
einundneunzig· ordinal: einundneunzigste
English
ninety-one· ordinal: ninety-first
Spanish
noventa y uno· ordinal: 91º
French
quatre-vingt-onze· ordinal: quatre-vingt-onzième
Italian
novantuno· ordinal: 91º
Latin
nonaginta unus· ordinal: 91.
Portuguese
noventa e um· ordinal: 91º

Appears in sequences