21255552142660 has 48 divisors (see below), whose sum is σ = 48909051132480. Its totient is φ = 7695241927040.

The previous prime is 21255552142651. The next prime is 21255552142667. The reversal of 21255552142660 is 6624125555212.

It is a self number, because there is not a number n which added to its sum of digits gives 21255552142660.

It is not an unprimeable number, because it can be changed into a prime (21255552142667) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 212760955 + ... + 212860834.

It is an arithmetic number, because the mean of its divisors is an integer number (1018938565260).

Almost surely, 2^{21255552142660} is an apocalyptic number.

21255552142660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21255552142660 is an abundant number, since it is smaller than the sum of its proper divisors (27653498989820).

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

21255552142660 is a wasteful number, since it uses less digits than its factorization.

21255552142660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 425622036 (or 425622034 counting only the distinct ones).

The product of its (nonzero) digits is 1440000, while the sum is 46.

Adding to 21255552142660 its reverse (6624125555212), we get a palindrome (27879677697872).

The spelling of 21255552142660 in words is "twenty-one trillion, two hundred fifty-five billion, five hundred fifty-two million, one hundred forty-two thousand, six hundred sixty".