99721788 has 12 divisors (see below), whose sum is σ = 232684200. Its totient is φ = 33240592.

The previous prime is 99721777. The next prime is 99721789. The reversal of 99721788 is 88712799.

It is a tau number, because it is divible by the number of its divisors (12).

It is a self number, because there is not a number n which added to its sum of digits gives 99721788.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (99721789) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4155063 + ... + 4155086.

It is an arithmetic number, because the mean of its divisors is an integer number (19390350).

Almost surely, 2^99721788 is an apocalyptic number.

It is an amenable number.

99721788 is an abundant number, since it is smaller than the sum of its proper divisors (132962412).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

99721788 is a wasteful number, since it uses less digits than its factorization.

99721788 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8310156 (or 8310154 counting only the distinct ones).

The product of its digits is 508032, while the sum is 51.

The square root of 99721788 is about 9986.0797112781. The cubic root of 99721788 is about 463.7280349858.

The spelling of 99721788 in words is "ninety-nine million, seven hundred twenty-one thousand, seven hundred eighty-eight".