99663648721 has 16 divisors (see below), whose sum is σ = 122687488000. Its totient is φ = 78838982208.

The previous prime is 99663648719. The next prime is 99663648767. The reversal of 99663648721 is 12784636699.

It is not a de Polignac number, because 99663648721 - 2¹ = 99663648719 is a prime.

It is the 315696-th Hogben number.

It is a self number, because there is not a number n which added to its sum of digits gives 99663648721.

It is not an unprimeable number, because it can be changed into a prime (99663648701) by changing a digit.

It is a nontrivial repunit in base 315695.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 358855 + ... + 572803.

It is an arithmetic number, because the mean of its divisors is an integer number (7667968000).

Almost surely, 2^99663648721 is an apocalyptic number.

99663648721 is a gapful number since it is divisible by the number (91) formed by its first and last digit.

It is an amenable number.

99663648721 is a deficient number, since it is larger than the sum of its proper divisors (23023839279).

99663648721 is a wasteful number, since it uses less digits than its factorization.

99663648721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 219088.

The product of its digits is 23514624, while the sum is 61.

The spelling of 99663648721 in words is "ninety-nine billion, six hundred sixty-three million, six hundred forty-eight thousand, seven hundred twenty-one".