21216020554464 has 96 divisors (see below), whose sum is σ = 57231800930304. Its totient is φ = 6877895162880.

The previous prime is 21216020554427. The next prime is 21216020554499. The reversal of 21216020554464 is 46445502061212.

It is a tau number, because it is divible by the number of its divisors (96).

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, 10067232 + ... + 11990879.

It is an arithmetic number, because the mean of its divisors is an integer number (596164593024).

Almost surely, 2^{21216020554464} is an apocalyptic number.

21216020554464 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21216020554464 is an abundant number, since it is smaller than the sum of its proper divisors (36015780375840).

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

21216020554464 is a wasteful number, since it uses less digits than its factorization.

21216020554464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22058400 (or 22058392 counting only the distinct ones).

The product of its (nonzero) digits is 460800, while the sum is 42.

The spelling of 21216020554464 in words is "twenty-one trillion, two hundred sixteen billion, twenty million, five hundred fifty-four thousand, four hundred sixty-four".