640475 has 24 divisors (see below), whose sum is σ = 924048. Its totient is φ = 435200.

The previous prime is 640463. The next prime is 640477. The reversal of 640475 is 574046.

It is not a de Polignac number, because 640475 - 2⁶ = 640411 is a prime.

It is a hoax number, since the sum of its digits (26) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 640475.

It is not an unprimeable number, because it can be changed into a prime (640477) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4607 + ... + 4743.

It is an arithmetic number, because the mean of its divisors is an integer number (38502).

2⁶⁴⁰⁴⁷⁵ is an apocalyptic number.

640475 is a deficient number, since it is larger than the sum of its proper divisors (283573).

640475 is a wasteful number, since it uses less digits than its factorization.

640475 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 175 (or 170 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 26.

The square root of 640475 is about 800.2968199362. The cubic root of 640475 is about 86.1987022556.

The spelling of 640475 in words is "six hundred forty thousand, four hundred seventy-five".