644959 has 8 divisors (see below), whose sum is σ = 742400. Its totient is φ = 548856.

The previous prime is 644951. The next prime is 644977. The reversal of 644959 is 959446.

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

It is not a de Polignac number, because 644959 - 2³ = 644951 is a prime.

It is a super-2 number, since 2×644959² = 831944223362, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644951) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1162 + ... + 1624.

It is an arithmetic number, because the mean of its divisors is an integer number (92800).

2⁶⁴⁴⁹⁵⁹ is an apocalyptic number.

644959 is a deficient number, since it is larger than the sum of its proper divisors (97441).

644959 is a wasteful number, since it uses less digits than its factorization.

644959 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 669.

The product of its digits is 38880, while the sum is 37.

The square root of 644959 is about 803.0933943197. The cubic root of 644959 is about 86.3993952147.

The spelling of 644959 in words is "six hundred forty-four thousand, nine hundred fifty-nine".