91531 has 8 divisors (see below), whose sum is σ = 102384. Its totient is φ = 81120.

The previous prime is 91529. The next prime is 91541. The reversal of 91531 is 13519.

91531 = T₈₀ + T₈₁ + ... + T₁₀₁.

91531 = 121² + 122² + ... + 126².

91531 is nontrivially palindromic in base 15.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 91531 - 2¹ = 91529 is a prime.

It is a super-2 number, since 2×91531² = 16755847922, which contains 22 as substring.

It is a Duffinian number.

91531 is an undulating number in base 15.

91531 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 91499 and 91508.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91541) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 505 + ... + 661.

It is an arithmetic number, because the mean of its divisors is an integer number (12798).

2⁹¹⁵³¹ is an apocalyptic number.

91531 is a deficient number, since it is larger than the sum of its proper divisors (10853).

91531 is a wasteful number, since it uses less digits than its factorization.

91531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 221.

The product of its digits is 135, while the sum is 19.

The square root of 91531 is about 302.5409063251. The cubic root of 91531 is about 45.0667322669.

It can be divided in two parts, 915 and 31, that added together give a triangular number (946 = T₄₃).

The spelling of 91531 in words is "ninety-one thousand, five hundred thirty-one".