640748687 has 2 divisors, whose sum is σ = 640748688. Its totient is φ = 640748686.

The previous prime is 640748663. The next prime is 640748699. The reversal of 640748687 is 786847046.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 640748687 - 2⁶ = 640748623 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640741687) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320374343 + 320374344.

It is an arithmetic number, because the mean of its divisors is an integer number (320374344).

Almost surely, 2^640748687 is an apocalyptic number.

640748687 is a deficient number, since it is larger than the sum of its proper divisors (1).

640748687 is an equidigital number, since it uses as much as digits as its factorization.

640748687 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1806336, while the sum is 50.

The square root of 640748687 is about 25313.0141824319. The cubic root of 640748687 is about 862.1097861543.

The spelling of 640748687 in words is "six hundred forty million, seven hundred forty-eight thousand, six hundred eighty-seven".