644437 has 4 divisors (see below), whose sum is σ = 672480. Its totient is φ = 616396.

The previous prime is 644431. The next prime is 644443. The reversal of 644437 is 734446.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (644431) and next prime (644443).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644437 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644431) 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 3 ways as a sum of consecutive naturals, for example, 13987 + ... + 14032.

It is an arithmetic number, because the mean of its divisors is an integer number (168120).

2⁶⁴⁴⁴³⁷ is an apocalyptic number.

It is an amenable number.

644437 is a deficient number, since it is larger than the sum of its proper divisors (28043).

644437 is a wasteful number, since it uses less digits than its factorization.

644437 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28042.

The product of its digits is 8064, while the sum is 28.

The square root of 644437 is about 802.7683352001. The cubic root of 644437 is about 86.3760796979.

Subtracting 644437 from its reverse (734446), we obtain a palindrome (90009).

It can be divided in two parts, 644 and 437, that added together give a triangular number (1081 = T₄₆).

The spelling of 644437 in words is "six hundred forty-four thousand, four hundred thirty-seven".