91497092721 has 16 divisors (see below), whose sum is σ = 129595118400. Its totient is φ = 57257471808.

The previous prime is 91497092707. The next prime is 91497092749. The reversal of 91497092721 is 12729079419.

It is a happy number.

It is a de Polignac number, because none of the positive numbers 2^k-91497092721 is a prime.

It is not an unprimeable number, because it can be changed into a prime (91497012721) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7357146 + ... + 7369571.

It is an arithmetic number, because the mean of its divisors is an integer number (8099694900).

Almost surely, 2^91497092721 is an apocalyptic number.

It is an amenable number.

91497092721 is a deficient number, since it is larger than the sum of its proper divisors (38098025679).

91497092721 is a wasteful number, since it uses less digits than its factorization.

91497092721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14726848.

The product of its (nonzero) digits is 571536, while the sum is 51.

The spelling of 91497092721 in words is "ninety-one billion, four hundred ninety-seven million, ninety-two thousand, seven hundred twenty-one".