9921157985 has 16 divisors (see below), whose sum is σ = 12758777856. Its totient is φ = 7386654528.

The previous prime is 9921157979. The next prime is 9921157999. The reversal of 9921157985 is 5897511299.

It is a cyclic number.

It is not a de Polignac number, because 9921157985 - 2¹⁰ = 9921156961 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 9921157985.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1161569 + ... + 1170078.

It is an arithmetic number, because the mean of its divisors is an integer number (797423616).

Almost surely, 2^9921157985 is an apocalyptic number.

It is an amenable number.

9921157985 is a deficient number, since it is larger than the sum of its proper divisors (2837619871).

9921157985 is a wasteful number, since it uses less digits than its factorization.

9921157985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2331712.

The product of its digits is 2041200, while the sum is 56.

The square root of 9921157985 is about 99605.0098388630. The cubic root of 9921157985 is about 2148.7577453253.

The spelling of 9921157985 in words is "nine billion, nine hundred twenty-one million, one hundred fifty-seven thousand, nine hundred eighty-five".