21551002504 has 8 divisors (see below), whose sum is σ = 40408129710. Its totient is φ = 10775501248.

The previous prime is 21551002469. The next prime is 21551002523. The reversal of 21551002504 is 40520015512.

It can be written as a sum of positive squares in only one way, i.e., 20297700900 + 1253301604 = 142470^2 + 35402^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1346937649 + ... + 1346937664.

Almost surely, 2^21551002504 is an apocalyptic number.

It is an amenable number.

21551002504 is a deficient number, since it is larger than the sum of its proper divisors (18857127206).

21551002504 is a wasteful number, since it uses less digits than its factorization.

21551002504 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2693875319 (or 2693875315 counting only the distinct ones).

The product of its (nonzero) digits is 2000, while the sum is 25.

The spelling of 21551002504 in words is "twenty-one billion, five hundred fifty-one million, two thousand, five hundred four".