640734173 has 2 divisors, whose sum is σ = 640734174. Its totient is φ = 640734172.

The previous prime is 640734167. The next prime is 640734239. The reversal of 640734173 is 371437046.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 601132324 + 39601849 = 24518^2 + 6293^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640734173 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640737173) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320367086 + 320367087.

It is an arithmetic number, because the mean of its divisors is an integer number (320367087).

Almost surely, 2^640734173 is an apocalyptic number.

It is an amenable number.

640734173 is a deficient number, since it is larger than the sum of its proper divisors (1).

640734173 is an equidigital number, since it uses as much as digits as its factorization.

640734173 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 42336, while the sum is 35.

The square root of 640734173 is about 25312.7274903358. The cubic root of 640734173 is about 862.1032767088.

The spelling of 640734173 in words is "six hundred forty million, seven hundred thirty-four thousand, one hundred seventy-three".