99921738815 has 64 divisors (see below), whose sum is σ = 129242234880. Its totient is φ = 73945872000.

The previous prime is 99921738809. The next prime is 99921738817. The reversal of 99921738815 is 51883712999.

It is a Cunningham number, because it is equal to 316104²-1.

It is not a de Polignac number, because 99921738815 - 2²² = 99917544511 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (99921738817) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 301878200 + ... + 301878530.

It is an arithmetic number, because the mean of its divisors is an integer number (2019409920).

Almost surely, 2^99921738815 is an apocalyptic number.

99921738815 is a gapful number since it is divisible by the number (95) formed by its first and last digit.

99921738815 is a deficient number, since it is larger than the sum of its proper divisors (29320496065).

99921738815 is a wasteful number, since it uses less digits than its factorization.

99921738815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 804.

The product of its digits is 9797760, while the sum is 62.

The spelling of 99921738815 in words is "ninety-nine billion, nine hundred twenty-one million, seven hundred thirty-eight thousand, eight hundred fifteen".