640356235 has 4 divisors (see below), whose sum is σ = 768427488. Its totient is φ = 512284984.

The previous prime is 640356209. The next prime is 640356251. The reversal of 640356235 is 532653046.

640356235 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 532653046 = 2 ⋅266326523.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640356235 is a prime.

It is a super-2 number, since 2×640356235² = 820112215406750450, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 640356235.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64035619 + ... + 64035628.

It is an arithmetic number, because the mean of its divisors is an integer number (192106872).

Almost surely, 2^640356235 is an apocalyptic number.

640356235 is a deficient number, since it is larger than the sum of its proper divisors (128071253).

640356235 is a wasteful number, since it uses less digits than its factorization.

640356235 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128071252.

The product of its (nonzero) digits is 64800, while the sum is 34.

The square root of 640356235 is about 25305.2610142634. The cubic root of 640356235 is about 861.9337390726.

The spelling of 640356235 in words is "six hundred forty million, three hundred fifty-six thousand, two hundred thirty-five".