99999972 has 36 divisors (see below), whose sum is σ = 253120140. Its totient is φ = 33288192.

The previous prime is 99999971. The next prime is 99999989. The reversal of 99999972 is 27999999.

It can be written as a sum of positive squares in 2 ways, for example, as 65707236 + 34292736 = 8106^2 + 5856^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a nialpdrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (99999971) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 34948 + ... + 37700.

It is an arithmetic number, because the mean of its divisors is an integer number (7031115).

Almost surely, 2^99999972 is an apocalyptic number.

It is an amenable number.

99999972 is an abundant number, since it is smaller than the sum of its proper divisors (153120168).

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

99999972 is a wasteful number, since it uses less digits than its factorization.

99999972 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3772 (or 3767 counting only the distinct ones).

The product of its digits is 7440174, while the sum is 63.

The square root of 99999972 is about 9999.9985999999. The cubic root of 99999972 is about 464.1588400398.

It can be divided in two parts, 9999997 and 2, that added together give a palindrome (9999999).

The spelling of 99999972 in words is "ninety-nine million, nine hundred ninety-nine thousand, nine hundred seventy-two".