640834705 has 8 divisors (see below), whose sum is σ = 878859072. Its totient is φ = 439429488.

The previous prime is 640834693. The next prime is 640834723. The reversal of 640834705 is 507438046.

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-640834705 is a prime.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 9154747 + ... + 9154816.

It is an arithmetic number, because the mean of its divisors is an integer number (109857384).

Almost surely, 2^640834705 is an apocalyptic number.

It is an amenable number.

640834705 is a deficient number, since it is larger than the sum of its proper divisors (238024367).

640834705 is a wasteful number, since it uses less digits than its factorization.

640834705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18309575.

The product of its (nonzero) digits is 80640, while the sum is 37.

The square root of 640834705 is about 25314.7132118853. The cubic root of 640834705 is about 862.1483627147.

The spelling of 640834705 in words is "six hundred forty million, eight hundred thirty-four thousand, seven hundred five".