91311531 has 4 divisors (see below), whose sum is σ = 121748712. Its totient is φ = 60874352.

The previous prime is 91311503. The next prime is 91311547. The reversal of 91311531 is 13511319.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 91311531 - 2¹⁴ = 91295147 is a prime.

It is a super-2 number, since 2×91311531² = 16675591387127922, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (91311631) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15218586 + ... + 15218591.

It is an arithmetic number, because the mean of its divisors is an integer number (30437178).

Almost surely, 2^91311531 is an apocalyptic number.

91311531 is a deficient number, since it is larger than the sum of its proper divisors (30437181).

91311531 is a wasteful number, since it uses less digits than its factorization.

91311531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30437180.

The product of its digits is 405, while the sum is 24.

The square root of 91311531 is about 9555.7067242565. The cubic root of 91311531 is about 450.3068376453.

The spelling of 91311531 in words is "ninety-one million, three hundred eleven thousand, five hundred thirty-one".