640725705 has 12 divisors (see below), whose sum is σ = 1110591300. Its totient is φ = 341720352.

The previous prime is 640725691. The next prime is 640725713. The reversal of 640725705 is 507527046.

640725705 is a `hidden beast` number, since 640 + 7 + 2 + 5 + 7 + 0 + 5 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 362102841 + 278622864 = 19029^2 + 16692^2 .

It is not a de Polignac number, because 640725705 - 2⁴ = 640725689 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 640725705.

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 11 ways as a sum of consecutive naturals, for example, 7119130 + ... + 7119219.

It is an arithmetic number, because the mean of its divisors is an integer number (92549275).

Almost surely, 2^640725705 is an apocalyptic number.

It is an amenable number.

640725705 is a deficient number, since it is larger than the sum of its proper divisors (469865595).

640725705 is a wasteful number, since it uses less digits than its factorization.

640725705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14238360 (or 14238357 counting only the distinct ones).

The product of its (nonzero) digits is 58800, while the sum is 36.

The square root of 640725705 is about 25312.5602221506. The cubic root of 640725705 is about 862.0994788141.

The spelling of 640725705 in words is "six hundred forty million, seven hundred twenty-five thousand, seven hundred five".