91518921 has 24 divisors (see below), whose sum is σ = 145681536. Its totient is φ = 55006560.

The previous prime is 91518883. The next prime is 91518949. The reversal of 91518921 is 12981519.

It is not a de Polignac number, because 91518921 - 2⁶ = 91518857 is a prime.

It is not an unprimeable number, because it can be changed into a prime (91511921) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4065 + ... + 14126.

It is an arithmetic number, because the mean of its divisors is an integer number (6070064).

Almost surely, 2^91518921 is an apocalyptic number.

It is an amenable number.

91518921 is a deficient number, since it is larger than the sum of its proper divisors (54162615).

91518921 is a wasteful number, since it uses less digits than its factorization.

91518921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18253 (or 18250 counting only the distinct ones).

The product of its digits is 6480, while the sum is 36.

The square root of 91518921 is about 9566.5522002443. The cubic root of 91518921 is about 450.6474975094.

The spelling of 91518921 in words is "ninety-one million, five hundred eighteen thousand, nine hundred twenty-one".