21555774768 has 40 divisors (see below), whose sum is σ = 60748094016. Its totient is φ = 6532052800.

The previous prime is 21555774761. The next prime is 21555774781. The reversal of 21555774768 is 86747755512.

It is not an unprimeable number, because it can be changed into a prime (21555774761) 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, 20412138 + ... + 20413193.

Almost surely, 2^21555774768 is an apocalyptic number.

It is an amenable number.

21555774768 is an abundant number, since it is smaller than the sum of its proper divisors (39192319248).

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

21555774768 is a wasteful number, since it uses less digits than its factorization.

21555774768 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40825353 (or 40825347 counting only the distinct ones).

The product of its digits is 16464000, while the sum is 57.

The spelling of 21555774768 in words is "twenty-one billion, five hundred fifty-five million, seven hundred seventy-four thousand, seven hundred sixty-eight".