99736587721 has 3 divisors (see below), whose sum is σ = 99736903533. Its totient is φ = 99736271910.

The previous prime is 99736587703. The next prime is 99736587733. The reversal of 99736587721 is 12778563799.

The square root of 99736587721 is 315811.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12778563799 = 29 ⋅440640131.

It is not a de Polignac number, because 99736587721 - 2⁵ = 99736587689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (99736587221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 157906 + ... + 473716.

It is an arithmetic number, because the mean of its divisors is an integer number (33245634511).

Almost surely, 2^99736587721 is an apocalyptic number.

99736587721 is the 315811-st square number.

99736587721 is the 157906-th centered octagonal number.

It is an amenable number.

99736587721 is a deficient number, since it is larger than the sum of its proper divisors (315812).

99736587721 is an frugal number, since it uses more digits than its factorization.

99736587721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 631622 (or 315811 counting only the distinct ones).

The product of its digits is 40007520, while the sum is 64.

Multiplying 99736587721 by its sum of digits (64), we get a square (6383141614144 = 2526488²).

The spelling of 99736587721 in words is "ninety-nine billion, seven hundred thirty-six million, five hundred eighty-seven thousand, seven hundred twenty-one".