99999998640 has 120 divisors (see below), whose sum is σ = 341338943088. Its totient is φ = 26229496320.

The previous prime is 99999998639. The next prime is 99999998641. The reversal of 99999998640 is 4689999999.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (99999998639) and next prime (99999998641).

It is a tau number, because it is divible by the number of its divisors (120).

It is a nialpdrome in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 99999998640.

It is not an unprimeable number, because it can be changed into a prime (99999998641) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1094514 + ... + 1182353.

Almost surely, 2^99999998640 is an apocalyptic number.

99999998640 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

99999998640 is an abundant number, since it is smaller than the sum of its proper divisors (241338944448).

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

99999998640 is a wasteful number, since it uses less digits than its factorization.

99999998640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2276947 (or 2276938 counting only the distinct ones).

The product of its (nonzero) digits is 918330048, while the sum is 81.

The spelling of 99999998640 in words is "ninety-nine billion, nine hundred ninety-nine million, nine hundred ninety-eight thousand, six hundred forty".