640437 has 8 divisors (see below), whose sum is σ = 975936. Its totient is φ = 365952.

The previous prime is 640421. The next prime is 640457. The reversal of 640437 is 734046.

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

It is not a de Polignac number, because 640437 - 2⁴ = 640421 is a prime.

640437 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640457) 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 7 ways as a sum of consecutive naturals, for example, 15228 + ... + 15269.

It is an arithmetic number, because the mean of its divisors is an integer number (121992).

2⁶⁴⁰⁴³⁷ is an apocalyptic number.

It is an amenable number.

640437 is a deficient number, since it is larger than the sum of its proper divisors (335499).

640437 is a wasteful number, since it uses less digits than its factorization.

640437 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30507.

The product of its (nonzero) digits is 2016, while the sum is 24.

The square root of 640437 is about 800.2730783926. The cubic root of 640437 is about 86.1969974712.

It can be divided in two parts, 6404 and 37, that added together give a triangular number (6441 = T₁₁₃).

The spelling of 640437 in words is "six hundred forty thousand, four hundred thirty-seven".