521644337247664 has 20 divisors (see below), whose sum is σ = 1010806755751656. Its totient is φ = 260790980924672.

The previous prime is 521644337247641. The next prime is 521644337247821. The reversal of 521644337247664 is 466742733446125.

It is a super-2 number, since 2×521644337247664² (a number of 30 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 521644337247596 and 521644337247605.

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, 1949093209 + ... + 1949360824.

Almost surely, 2^{521644337247664} is an apocalyptic number.

It is an amenable number.

521644337247664 is a deficient number, since it is larger than the sum of its proper divisors (489162418503992).

521644337247664 is a wasteful number, since it uses less digits than its factorization.

521644337247664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3898462404 (or 3898462398 counting only the distinct ones).

The product of its digits is 487710720, while the sum is 64.

The spelling of 521644337247664 in words is "five hundred twenty-one trillion, six hundred forty-four billion, three hundred thirty-seven million, two hundred forty-seven thousand, six hundred sixty-four".