99515642521 has 3 divisors (see below), whose sum is σ = 99515957983. Its totient is φ = 99515327060.

The previous prime is 99515642519. The next prime is 99515642531. The reversal of 99515642521 is 12524651599.

The square root of 99515642521 is 315461.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 21685802121 + 77829840400 = 147261^2 + 278980^2 .

It is not a de Polignac number, because 99515642521 - 2¹ = 99515642519 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (99515642531) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 157731 + ... + 473191.

Almost surely, 2^99515642521 is an apocalyptic number.

99515642521 is the 315461-st square number.

99515642521 is the 157731-st centered octagonal number.

It is an amenable number.

99515642521 is a deficient number, since it is larger than the sum of its proper divisors (315462).

99515642521 is an frugal number, since it uses more digits than its factorization.

99515642521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 630922 (or 315461 counting only the distinct ones).

The product of its digits is 972000, while the sum is 49.

Multiplying 99515642521 by its sum of digits (49), we get a square (4876266483529 = 2208227²).

The spelling of 99515642521 in words is "ninety-nine billion, five hundred fifteen million, six hundred forty-two thousand, five hundred twenty-one".