640344405 has 16 divisors (see below), whose sum is σ = 1041917760. Its totient is φ = 335728128.

The previous prime is 640344361. The next prime is 640344451. The reversal of 640344405 is 504443046.

It is not a de Polignac number, because 640344405 - 2⁸ = 640344149 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 360892 + ... + 362661.

It is an arithmetic number, because the mean of its divisors is an integer number (65119860).

Almost surely, 2^640344405 is an apocalyptic number.

It is an amenable number.

640344405 is a deficient number, since it is larger than the sum of its proper divisors (401573355).

640344405 is a wasteful number, since it uses less digits than its factorization.

640344405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 723620.

The product of its (nonzero) digits is 23040, while the sum is 30.

The square root of 640344405 is about 25305.0272673238. The cubic root of 640344405 is about 861.9284312255.

The spelling of 640344405 in words is "six hundred forty million, three hundred forty-four thousand, four hundred five".