99538721 has 4 divisors (see below), whose sum is σ = 100149552. Its totient is φ = 98927892.

The previous prime is 99538709. The next prime is 99538727. The reversal of 99538721 is 12783599.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-99538721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (99538727) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 305171 + ... + 305496.

It is an arithmetic number, because the mean of its divisors is an integer number (25037388).

Almost surely, 2^99538721 is an apocalyptic number.

It is an amenable number.

99538721 is a deficient number, since it is larger than the sum of its proper divisors (610831).

99538721 is a wasteful number, since it uses less digits than its factorization.

99538721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 610830.

The product of its digits is 136080, while the sum is 44.

The square root of 99538721 is about 9976.9093911892. The cubic root of 99538721 is about 463.4440940225. Note that the first 3 decimals are identical.

The spelling of 99538721 in words is "ninety-nine million, five hundred thirty-eight thousand, seven hundred twenty-one".