21218365657338 has 64 divisors (see below), whose sum is σ = 45890445500928. Its totient is φ = 6514908549120.

The previous prime is 21218365657337. The next prime is 21218365657421. The reversal of 21218365657338 is 83375656381212.

It is not an unprimeable number, because it can be changed into a prime (21218365657337) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 254812206 + ... + 254895462.

It is an arithmetic number, because the mean of its divisors is an integer number (717038210952).

Almost surely, 2^{21218365657338} is an apocalyptic number.

21218365657338 is an abundant number, since it is smaller than the sum of its proper divisors (24672079843590).

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

21218365657338 is a wasteful number, since it uses less digits than its factorization.

21218365657338 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136487.

The product of its digits is 43545600, while the sum is 60.

The spelling of 21218365657338 in words is "twenty-one trillion, two hundred eighteen billion, three hundred sixty-five million, six hundred fifty-seven thousand, three hundred thirty-eight".