21218534458464 has 384 divisors, whose sum is σ = 69782808130560. Its totient is φ = 5504440467456.

The previous prime is 21218534458411. The next prime is 21218534458487. The reversal of 21218534458464 is 46485443581212.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 403160919 + ... + 403213545.

It is an arithmetic number, because the mean of its divisors is an integer number (181726062840).

Almost surely, 2^{21218534458464} is an apocalyptic number.

21218534458464 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21218534458464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34891404065280).

21218534458464 is an abundant number, since it is smaller than the sum of its proper divisors (48564273672096).

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

21218534458464 is a wasteful number, since it uses less digits than its factorization.

21218534458464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53910 (or 53902 counting only the distinct ones).

The product of its digits is 29491200, while the sum is 57.

The spelling of 21218534458464 in words is "twenty-one trillion, two hundred eighteen billion, five hundred thirty-four million, four hundred fifty-eight thousand, four hundred sixty-four".