647640667 has 4 divisors (see below), whose sum is σ = 649445040. Its totient is φ = 645836296.

The previous prime is 647640659. The next prime is 647640671. The reversal of 647640667 is 766046746.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 647640667 - 2³ = 647640659 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (647640607) 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, 901648 + ... + 902365.

It is an arithmetic number, because the mean of its divisors is an integer number (162361260).

Almost surely, 2^647640667 is an apocalyptic number.

647640667 is a deficient number, since it is larger than the sum of its proper divisors (1804373).

647640667 is a wasteful number, since it uses less digits than its factorization.

647640667 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1804372.

The product of its (nonzero) digits is 1016064, while the sum is 46.

The square root of 647640667 is about 25448.7851772928. The cubic root of 647640667 is about 865.1897595646.

The spelling of 647640667 in words is "six hundred forty-seven million, six hundred forty thousand, six hundred sixty-seven".