21521042455 has 48 divisors (see below), whose sum is σ = 30003523200. Its totient is φ = 14766840000.

The previous prime is 21521042453. The next prime is 21521042467. The reversal of 21521042455 is 55424012512.

It is not a de Polignac number, because 21521042455 - 2¹ = 21521042453 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21521042453) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2881516 + ... + 2888974.

It is an arithmetic number, because the mean of its divisors is an integer number (625073400).

Almost surely, 2^21521042455 is an apocalyptic number.

21521042455 is a deficient number, since it is larger than the sum of its proper divisors (8482480745).

21521042455 is a wasteful number, since it uses less digits than its factorization.

21521042455 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7756 (or 7745 counting only the distinct ones).

The product of its (nonzero) digits is 16000, while the sum is 31.

Adding to 21521042455 its reverse (55424012512), we get a palindrome (76945054967).

The spelling of 21521042455 in words is "twenty-one billion, five hundred twenty-one million, forty-two thousand, four hundred fifty-five".