640344 has 16 divisors (see below), whose sum is σ = 1600920. Its totient is φ = 213440.

The previous prime is 640333. The next prime is 640363. The reversal of 640344 is 443046.

It is a super-3 number, since 3×640344³ = 787700803337482752, which contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 640344.

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 640344.

It is an unprimeable number.

640344 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13317 + ... + 13364.

2⁶⁴⁰³⁴⁴ is an apocalyptic number.

It is an amenable number.

640344 is an abundant number, since it is smaller than the sum of its proper divisors (960576).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

640344 is a wasteful number, since it uses less digits than its factorization.

640344 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26690 (or 26686 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 21.

The square root of 640344 is about 800.2149711171. The cubic root of 640344 is about 86.1928249510.

It can be divided in two parts, 6 and 40344, that multiplied together give a square (242064 = 492²).

The spelling of 640344 in words is "six hundred forty thousand, three hundred forty-four".