21555368159020 has 12 divisors (see below), whose sum is σ = 45266273133984. Its totient is φ = 8622147263600.

The previous prime is 21555368158967. The next prime is 21555368159041. The reversal of 21555368159020 is 2095186355512.

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, 538884203956 + ... + 538884203995.

It is an arithmetic number, because the mean of its divisors is an integer number (3772189427832).

Almost surely, 2^{21555368159020} is an apocalyptic number.

21555368159020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21555368159020 is an abundant number, since it is smaller than the sum of its proper divisors (23710904974964).

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

21555368159020 is a wasteful number, since it uses less digits than its factorization.

21555368159020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1077768407960 (or 1077768407958 counting only the distinct ones).

The product of its (nonzero) digits is 3240000, while the sum is 52.

The spelling of 21555368159020 in words is "twenty-one trillion, five hundred fifty-five billion, three hundred sixty-eight million, one hundred fifty-nine thousand, twenty".