21777917628 has 24 divisors (see below), whose sum is σ = 51070499200. Its totient is φ = 7222826160.

The previous prime is 21777917627. The next prime is 21777917657. The reversal of 21777917628 is 82671977712.

It is a Smith number, since the sum of its digits (57) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21777917621) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4557478 + ... + 4562253.

Almost surely, 2^21777917628 is an apocalyptic number.

It is an amenable number.

21777917628 is an abundant number, since it is smaller than the sum of its proper divisors (29292581572).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21777917628 is a wasteful number, since it uses less digits than its factorization.

21777917628 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9119937 (or 9119935 counting only the distinct ones).

The product of its digits is 4148928, while the sum is 57.

The spelling of 21777917628 in words is "twenty-one billion, seven hundred seventy-seven million, nine hundred seventeen thousand, six hundred twenty-eight".