640734409 has 16 divisors (see below), whose sum is σ = 751044096. Its totient is φ = 535219200.

The previous prime is 640734343. The next prime is 640734449. The reversal of 640734409 is 904437046.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640734409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640734449) 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 in 15 ways as a sum of consecutive naturals, for example, 75249 + ... + 83329.

It is an arithmetic number, because the mean of its divisors is an integer number (46940256).

Almost surely, 2^640734409 is an apocalyptic number.

It is an amenable number.

640734409 is a deficient number, since it is larger than the sum of its proper divisors (110309687).

640734409 is a wasteful number, since it uses less digits than its factorization.

640734409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8376.

The product of its (nonzero) digits is 72576, while the sum is 37.

The square root of 640734409 is about 25312.7321520218. The cubic root of 640734409 is about 862.1033825542.

The spelling of 640734409 in words is "six hundred forty million, seven hundred thirty-four thousand, four hundred nine".