21551338528 has 12 divisors (see below), whose sum is σ = 42429197790. Its totient is φ = 10775669248.

The previous prime is 21551338513. The next prime is 21551338531. The reversal of 21551338528 is 82583315512.

It can be written as a sum of positive squares in only one way, i.e., 11128562064 + 10422776464 = 105492^2 + 102092^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 336739633 + ... + 336739696.

Almost surely, 2^21551338528 is an apocalyptic number.

It is an amenable number.

21551338528 is a deficient number, since it is larger than the sum of its proper divisors (20877859262).

21551338528 is an equidigital number, since it uses as much as digits as its factorization.

21551338528 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 673479339 (or 673479331 counting only the distinct ones).

The product of its digits is 288000, while the sum is 43.

The spelling of 21551338528 in words is "twenty-one billion, five hundred fifty-one million, three hundred thirty-eight thousand, five hundred twenty-eight".