647521057491 has 24 divisors (see below), whose sum is σ = 1095620048064. Its totient is φ = 336374574480.

The previous prime is 647521057471. The next prime is 647521057493. The reversal of 647521057491 is 194750125746.

647521057491 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 647521057491 - 2⁹ = 647521056979 is a prime.

It is not an unprimeable number, because it can be changed into a prime (647521057493) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 200221345 + ... + 200224578.

It is an arithmetic number, because the mean of its divisors is an integer number (45650835336).

Almost surely, 2^647521057491 is an apocalyptic number.

647521057491 is a deficient number, since it is larger than the sum of its proper divisors (448098990573).

647521057491 is a wasteful number, since it uses less digits than its factorization.

647521057491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 400445951 (or 400445944 counting only the distinct ones).

The product of its (nonzero) digits is 2116800, while the sum is 51.

The spelling of 647521057491 in words is "six hundred forty-seven billion, five hundred twenty-one million, fifty-seven thousand, four hundred ninety-one".