640708023 has 4 divisors (see below), whose sum is σ = 854277368. Its totient is φ = 427138680.

The previous prime is 640708009. The next prime is 640708027. The reversal of 640708023 is 320807046.

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

It is not a de Polignac number, because 640708023 - 2¹⁶ = 640642487 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 (640708027) 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, 106784668 + ... + 106784673.

It is an arithmetic number, because the mean of its divisors is an integer number (213569342).

Almost surely, 2^640708023 is an apocalyptic number.

640708023 is a deficient number, since it is larger than the sum of its proper divisors (213569345).

640708023 is a wasteful number, since it uses less digits than its factorization.

640708023 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213569344.

The product of its (nonzero) digits is 8064, while the sum is 30.

The square root of 640708023 is about 25312.2109464977. The cubic root of 640708023 is about 862.0915483362.

The spelling of 640708023 in words is "six hundred forty million, seven hundred eight thousand, twenty-three".