644842 has 8 divisors (see below), whose sum is σ = 1055232. Its totient is φ = 293100.

The previous prime is 644837. The next prime is 644843. The reversal of 644842 is 248446.

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

It is a self number, because there is not a number n which added to its sum of digits gives 644842.

It is not an unprimeable number, because it can be changed into a prime (644843) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14634 + ... + 14677.

It is an arithmetic number, because the mean of its divisors is an integer number (131904).

2⁶⁴⁴⁸⁴² is an apocalyptic number.

644842 is a deficient number, since it is larger than the sum of its proper divisors (410390).

644842 is a wasteful number, since it uses less digits than its factorization.

644842 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29324.

The product of its digits is 6144, while the sum is 28.

The square root of 644842 is about 803.0205476823. The cubic root of 644842 is about 86.3941704171.

The spelling of 644842 in words is "six hundred forty-four thousand, eight hundred forty-two".