640624717 has 4 divisors (see below), whose sum is σ = 640896156. Its totient is φ = 640353280.

The previous prime is 640624687. The next prime is 640624723. The reversal of 640624717 is 717426046.

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

It can be written as a sum of positive squares in 2 ways, for example, as 32558436 + 608066281 = 5706^2 + 24659^2 .

It is a cyclic number.

It is not a de Polignac number, because 640624717 - 2¹⁵ = 640591949 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640624757) 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, 132148 + ... + 136909.

It is an arithmetic number, because the mean of its divisors is an integer number (160224039).

Almost surely, 2^640624717 is an apocalyptic number.

It is an amenable number.

640624717 is a deficient number, since it is larger than the sum of its proper divisors (271439).

640624717 is a wasteful number, since it uses less digits than its factorization.

640624717 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 271438.

The product of its (nonzero) digits is 56448, while the sum is 37.

The square root of 640624717 is about 25310.5653235956. The cubic root of 640624717 is about 862.0541831564.

The spelling of 640624717 in words is "six hundred forty million, six hundred twenty-four thousand, seven hundred seventeen".