21420767718864 has 60 divisors (see below), whose sum is σ = 59956969095556. Its totient is φ = 7139235096576.

The previous prime is 21420767718841. The next prime is 21420767718869. The reversal of 21420767718864 is 46881776702412.

21420767718864 is a `hidden beast` number, since 2 + 1 + 420 + 7 + 6 + 7 + 71 + 88 + 64 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 8429731560000 + 12991036158864 = 2903400^2 + 3604308^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21420767718869) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9622369 + ... + 11637504.

Almost surely, 2^{21420767718864} is an apocalyptic number.

21420767718864 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21420767718864 is an abundant number, since it is smaller than the sum of its proper divisors (38536201376692).

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

21420767718864 is a wasteful number, since it uses less digits than its factorization.

21420767718864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21266884 (or 21266875 counting only the distinct ones).

The product of its (nonzero) digits is 50577408, while the sum is 63.

The spelling of 21420767718864 in words is "twenty-one trillion, four hundred twenty billion, seven hundred sixty-seven million, seven hundred eighteen thousand, eight hundred sixty-four".