21555625685944 has 64 divisors (see below), whose sum is σ = 46858450636800. Its totient is φ = 9105447945600.

The previous prime is 21555625685927. The next prime is 21555625685977. The reversal of 21555625685944 is 44958652655512.

It is a happy number.

It is a super-2 number, since 2×21555625685944² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21555625685944.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8078622 + ... + 10410349.

It is an arithmetic number, because the mean of its divisors is an integer number (732163291200).

Almost surely, 2^{21555625685944} is an apocalyptic number.

It is an amenable number.

21555625685944 is an abundant number, since it is smaller than the sum of its proper divisors (25302824950856).

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

21555625685944 is a wasteful number, since it uses less digits than its factorization.

21555625685944 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18489284 (or 18489280 counting only the distinct ones).

The product of its digits is 518400000, while the sum is 67.

The spelling of 21555625685944 in words is "twenty-one trillion, five hundred fifty-five billion, six hundred twenty-five million, six hundred eighty-five thousand, nine hundred forty-four".