640431347 has 8 divisors (see below), whose sum is σ = 674596800. Its totient is φ = 606311784.

The previous prime is 640431329. The next prime is 640431377. The reversal of 640431347 is 743134046.

640431347 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640431347 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640431377) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19328 + ... + 40674.

It is an arithmetic number, because the mean of its divisors is an integer number (84324600).

Almost surely, 2^640431347 is an apocalyptic number.

640431347 is a deficient number, since it is larger than the sum of its proper divisors (34165453).

640431347 is a wasteful number, since it uses less digits than its factorization.

640431347 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22945.

The product of its (nonzero) digits is 24192, while the sum is 32.

The square root of 640431347 is about 25306.7450890074. The cubic root of 640431347 is about 861.9674385627.

The spelling of 640431347 in words is "six hundred forty million, four hundred thirty-one thousand, three hundred forty-seven".