640164731 has 8 divisors (see below), whose sum is σ = 643507200. Its totient is φ = 636831720.

The previous prime is 640164703. The next prime is 640164737. The reversal of 640164731 is 137461046.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 640164731 - 2¹⁴ = 640148347 is a prime.

It is a super-2 number, since 2×640164731² = 819621765632604722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640164737) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 161390 + ... + 165308.

It is an arithmetic number, because the mean of its divisors is an integer number (80438400).

Almost surely, 2^640164731 is an apocalyptic number.

640164731 is a deficient number, since it is larger than the sum of its proper divisors (3342469).

640164731 is a wasteful number, since it uses less digits than its factorization.

640164731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4729.

The product of its (nonzero) digits is 12096, while the sum is 32.

The square root of 640164731 is about 25301.4768541285. The cubic root of 640164731 is about 861.8478076243.

The spelling of 640164731 in words is "six hundred forty million, one hundred sixty-four thousand, seven hundred thirty-one".