640318705 has 16 divisors (see below), whose sum is σ = 843106320. Its totient is φ = 463926528.

The previous prime is 640318703. The next prime is 640318711. The reversal of 640318705 is 507813046.

It can be written as a sum of positive squares in 8 ways, for example, as 29289744 + 611028961 = 5412^2 + 24719^2 .

It is not a de Polignac number, because 640318705 - 2¹ = 640318703 is a prime.

It is not an unprimeable number, because it can be changed into a prime (640318703) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 89490 + ... + 96379.

It is an arithmetic number, because the mean of its divisors is an integer number (52694145).

Almost surely, 2^640318705 is an apocalyptic number.

640318705 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

640318705 is a deficient number, since it is larger than the sum of its proper divisors (202787615).

640318705 is a wasteful number, since it uses less digits than its factorization.

640318705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 185940.

The product of its (nonzero) digits is 20160, while the sum is 34.

The square root of 640318705 is about 25304.5194579941. The cubic root of 640318705 is about 861.9169000053.

The spelling of 640318705 in words is "six hundred forty million, three hundred eighteen thousand, seven hundred five".