21216361515504 has 20 divisors (see below), whose sum is σ = 54808933915176. Its totient is φ = 7072120505152.

The previous prime is 21216361515451. The next prime is 21216361515529. The reversal of 21216361515504 is 40551516361212.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 221003765739 + ... + 221003765834.

Almost surely, 2^{21216361515504} is an apocalyptic number.

21216361515504 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21216361515504 is an abundant number, since it is smaller than the sum of its proper divisors (33592572399672).

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

21216361515504 is a wasteful number, since it uses less digits than its factorization.

21216361515504 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 442007531584 (or 442007531578 counting only the distinct ones).

The product of its (nonzero) digits is 216000, while the sum is 42.

Adding to 21216361515504 its reverse (40551516361212), we get a palindrome (61767877876716).

The spelling of 21216361515504 in words is "twenty-one trillion, two hundred sixteen billion, three hundred sixty-one million, five hundred fifteen thousand, five hundred four".