21808571620 has 24 divisors (see below), whose sum is σ = 49961455488. Its totient is φ = 7930389600.

The previous prime is 21808571597. The next prime is 21808571627. The reversal of 21808571620 is 2617580812.

It is a super-2 number, since 2×21808571620² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21808571627) 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, 49564716 + ... + 49565155.

It is an arithmetic number, because the mean of its divisors is an integer number (2081727312).

Almost surely, 2^21808571620 is an apocalyptic number.

21808571620 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21808571620 is an abundant number, since it is smaller than the sum of its proper divisors (28152883868).

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

21808571620 is a wasteful number, since it uses less digits than its factorization.

21808571620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99129891 (or 99129889 counting only the distinct ones).

The product of its (nonzero) digits is 53760, while the sum is 40.

The spelling of 21808571620 in words is "twenty-one billion, eight hundred eight million, five hundred seventy-one thousand, six hundred twenty".