21557877508 has 48 divisors (see below), whose sum is σ = 40518656640. Its totient is φ = 10005465600.

The previous prime is 21557877503. The next prime is 21557877511. The reversal of 21557877508 is 80577875512.

It is a Smith number, since the sum of its digits (55) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (21557877503) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1210428 + ... + 1228108.

It is an arithmetic number, because the mean of its divisors is an integer number (844138680).

Almost surely, 2^21557877508 is an apocalyptic number.

It is an amenable number.

21557877508 is a deficient number, since it is larger than the sum of its proper divisors (18960779132).

21557877508 is a wasteful number, since it uses less digits than its factorization.

21557877508 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18028 (or 18026 counting only the distinct ones).

The product of its (nonzero) digits is 5488000, while the sum is 55.

The spelling of 21557877508 in words is "twenty-one billion, five hundred fifty-seven million, eight hundred seventy-seven thousand, five hundred eight".