521644021516 has 12 divisors (see below), whose sum is σ = 937549390288. Its totient is φ = 253772767152.

The previous prime is 521644021511. The next prime is 521644021529. The reversal of 521644021516 is 615120446125.

It is a super-2 number, since 2×521644021516² (a number of 24 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is not an unprimeable number, because it can be changed into a prime (521644021511) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1762310736 + ... + 1762311031.

Almost surely, 2^521644021516 is an apocalyptic number.

It is an amenable number.

521644021516 is a deficient number, since it is larger than the sum of its proper divisors (415905368772).

521644021516 is a wasteful number, since it uses less digits than its factorization.

521644021516 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3524621808 (or 3524621806 counting only the distinct ones).

The product of its (nonzero) digits is 57600, while the sum is 37.

The spelling of 521644021516 in words is "five hundred twenty-one billion, six hundred forty-four million, twenty-one thousand, five hundred sixteen".