21637616880 has 240 divisors, whose sum is σ = 76274180640. Its totient is φ = 5064407040.

The previous prime is 21637616849. The next prime is 21637616887. The reversal of 21637616880 is 8861673612.

It is a tau number, because it is divible by the number of its divisors (240).

It is a hoax number, since the sum of its digits (48) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21637616887) by changing a digit.

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 47 ways as a sum of consecutive naturals, for example, 829314 + ... + 855006.

It is an arithmetic number, because the mean of its divisors is an integer number (317809086).

Almost surely, 2^21637616880 is an apocalyptic number.

21637616880 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 21637616880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38137090320).

21637616880 is an abundant number, since it is smaller than the sum of its proper divisors (54636563760).

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

21637616880 is a wasteful number, since it uses less digits than its factorization.

21637616880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25760 (or 25743 counting only the distinct ones).

The product of its (nonzero) digits is 580608, while the sum is 48.

The spelling of 21637616880 in words is "twenty-one billion, six hundred thirty-seven million, six hundred sixteen thousand, eight hundred eighty".