21055478868 has 36 divisors (see below), whose sum is σ = 53305892640. Its totient is φ = 7007637456.

The previous prime is 21055478849. The next prime is 21055478887. The reversal of 21055478868 is 86887455012.

21055478868 is a `hidden beast` number, since 2 + 1 + 0 + 554 + 7 + 8 + 86 + 8 = 666.

It is an interprime number because it is at equal distance from previous prime (21055478849) and next prime (21055478887).

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×21055478868² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 428698 + ... + 475281.

It is an arithmetic number, because the mean of its divisors is an integer number (1480719240).

Almost surely, 2^21055478868 is an apocalyptic number.

It is an amenable number.

21055478868 is an abundant number, since it is smaller than the sum of its proper divisors (32250413772).

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

21055478868 is a wasteful number, since it uses less digits than its factorization.

21055478868 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 904636 (or 904631 counting only the distinct ones).

The product of its (nonzero) digits is 4300800, while the sum is 54.

The spelling of 21055478868 in words is "twenty-one billion, fifty-five million, four hundred seventy-eight thousand, eight hundred sixty-eight".