640874 has 12 divisors (see below), whose sum is σ = 1041894. Its totient is φ = 293904.

The previous prime is 640873. The next prime is 640891. The reversal of 640874 is 478046.

640874 = 216² + 217² + ... + 228².

640874 is nontrivially palindromic in base 12.

It can be written as a sum of positive squares in 3 ways, for example, as 310249 + 330625 = 557^2 + 575^2 .

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 640874.

It is not an unprimeable number, because it can be changed into a prime (640873) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4004 + ... + 4160.

2⁶⁴⁰⁸⁷⁴ is an apocalyptic number.

640874 is a deficient number, since it is larger than the sum of its proper divisors (401020).

640874 is a wasteful number, since it uses less digits than its factorization.

640874 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 329 (or 172 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 29.

The square root of 640874 is about 800.5460636341. The cubic root of 640874 is about 86.2165984226.

The spelling of 640874 in words is "six hundred forty thousand, eight hundred seventy-four".