99999721975 has 24 divisors (see below), whose sum is σ = 129017144160. Its totient is φ = 76794587520.

The previous prime is 99999721967. The next prime is 99999722021. The reversal of 99999721975 is 57912799999.

It is not a de Polignac number, because 99999721975 - 2³ = 99999721967 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 273219 + ... + 524068.

It is an arithmetic number, because the mean of its divisors is an integer number (5375714340).

Almost surely, 2^99999721975 is an apocalyptic number.

99999721975 is a deficient number, since it is larger than the sum of its proper divisors (29017422185).

99999721975 is a wasteful number, since it uses less digits than its factorization.

99999721975 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 797499 (or 797494 counting only the distinct ones).

The product of its digits is 260406090, while the sum is 76.

The spelling of 99999721975 in words is "ninety-nine billion, nine hundred ninety-nine million, seven hundred twenty-one thousand, nine hundred seventy-five".