21617162920 has 64 divisors (see below), whose sum is σ = 49898592000. Its totient is φ = 8425524480.

The previous prime is 21617162911. The next prime is 21617162969. The reversal of 21617162920 is 2926171612.

It is a self number, because there is not a number n which added to its sum of digits gives 21617162920.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 219681 + ... + 302479.

It is an arithmetic number, because the mean of its divisors is an integer number (779665500).

Almost surely, 2^21617162920 is an apocalyptic number.

21617162920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21617162920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24949296000).

21617162920 is an abundant number, since it is smaller than the sum of its proper divisors (28281429080).

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

21617162920 is a wasteful number, since it uses less digits than its factorization.

21617162920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82978 (or 82974 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 37.

The spelling of 21617162920 in words is "twenty-one billion, six hundred seventeen million, one hundred sixty-two thousand, nine hundred twenty".