640317457 has 8 divisors (see below), whose sum is σ = 689933160. Its totient is φ = 590753280.

The previous prime is 640317443. The next prime is 640317473. The reversal of 640317457 is 754713046.

It can be written as a sum of positive squares in 4 ways, for example, as 2047761 + 638269696 = 1431^2 + 25264^2 .

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

It is not a de Polignac number, because 640317457 - 2¹⁹ = 639793169 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640317407) 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, 15219 + ... + 38887.

It is an arithmetic number, because the mean of its divisors is an integer number (86241645).

Almost surely, 2^640317457 is an apocalyptic number.

It is an amenable number.

640317457 is a deficient number, since it is larger than the sum of its proper divisors (49615703).

640317457 is a wasteful number, since it uses less digits than its factorization.

640317457 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25763.

The product of its (nonzero) digits is 70560, while the sum is 37.

The square root of 640317457 is about 25304.4947983555. The cubic root of 640317457 is about 861.9163400378.

The spelling of 640317457 in words is "six hundred forty million, three hundred seventeen thousand, four hundred fifty-seven".