9257720991 has 32 divisors (see below), whose sum is σ = 13805180928. Its totient is φ = 5490616320.

The previous prime is 9257720977. The next prime is 9257721019. The reversal of 9257720991 is 1990277529.

It is not a de Polignac number, because 9257720991 - 2⁵ = 9257720959 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9257720921) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 106 + ... + 136071.

It is an arithmetic number, because the mean of its divisors is an integer number (431411904).

Almost surely, 2^9257720991 is an apocalyptic number.

9257720991 is a deficient number, since it is larger than the sum of its proper divisors (4547459937).

9257720991 is a wasteful number, since it uses less digits than its factorization.

9257720991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 136271.

The product of its (nonzero) digits is 714420, while the sum is 51.

The square root of 9257720991 is about 96217.0514565895. The cubic root of 9257720991 is about 2099.7521242576.

The spelling of 9257720991 in words is "nine billion, two hundred fifty-seven million, seven hundred twenty thousand, nine hundred ninety-one".