21817765608 has 16 divisors (see below), whose sum is σ = 54544414080. Its totient is φ = 7272588528.

The previous prime is 21817765597. The next prime is 21817765633. The reversal of 21817765608 is 80656771812.

It is a happy number.

It is a super-2 number, since 2×21817765608² (a number of 21 digits) contains 22 as substring.

It is a hoax number, since the sum of its digits (51) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 454536760 + ... + 454536807.

It is an arithmetic number, because the mean of its divisors is an integer number (3409025880).

Almost surely, 2^21817765608 is an apocalyptic number.

It is an amenable number.

21817765608 is an abundant number, since it is smaller than the sum of its proper divisors (32726648472).

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

21817765608 is a wasteful number, since it uses less digits than its factorization.

21817765608 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 909073576 (or 909073572 counting only the distinct ones).

The product of its (nonzero) digits is 1128960, while the sum is 51.

The spelling of 21817765608 in words is "twenty-one billion, eight hundred seventeen million, seven hundred sixty-five thousand, six hundred eight".