21216504253 has 32 divisors (see below), whose sum is σ = 25934929920. Its totient is φ = 16973686080.

The previous prime is 21216504193. The next prime is 21216504263. The reversal of 21216504253 is 35240561212.

It is a cyclic number.

It is not a de Polignac number, because 21216504253 - 2²¹ = 21214407101 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21216504263) 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, 662926 + ... + 694192.

It is an arithmetic number, because the mean of its divisors is an integer number (810466560).

Almost surely, 2^21216504253 is an apocalyptic number.

It is an amenable number.

21216504253 is a deficient number, since it is larger than the sum of its proper divisors (4718425667).

21216504253 is a wasteful number, since it uses less digits than its factorization.

21216504253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31417.

The product of its (nonzero) digits is 14400, while the sum is 31.

The spelling of 21216504253 in words is "twenty-one billion, two hundred sixteen million, five hundred four thousand, two hundred fifty-three".