9999998640 has 80 divisors (see below), whose sum is σ = 34444447200. Its totient is φ = 2666665728.

The previous prime is 9999998633. The next prime is 9999998641. The reversal of 9999998640 is 468999999.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a nialpdrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (9999998641) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2312655 + ... + 2316974.

It is an arithmetic number, because the mean of its divisors is an integer number (430555590).

Almost surely, 2^9999998640 is an apocalyptic number.

9999998640 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

9999998640 is an abundant number, since it is smaller than the sum of its proper divisors (24444448560).

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

9999998640 is a wasteful number, since it uses less digits than its factorization.

9999998640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4629651 (or 4629639 counting only the distinct ones).

The product of its (nonzero) digits is 102036672, while the sum is 72.

The square root of 9999998640 is about 99999.9931999998. The cubic root of 9999998640 is about 2154.4345923642.

The spelling of 9999998640 in words is "nine billion, nine hundred ninety-nine million, nine hundred ninety-eight thousand, six hundred forty".