644841 has 20 divisors (see below), whose sum is σ = 1016400. Its totient is φ = 406296.

The previous prime is 644837. The next prime is 644843. The reversal of 644841 is 148446.

It is not a de Polignac number, because 644841 - 2² = 644837 is a prime.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

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 19 ways as a sum of consecutive naturals, for example, 1330 + ... + 1748.

It is an arithmetic number, because the mean of its divisors is an integer number (50820).

2⁶⁴⁴⁸⁴¹ is an apocalyptic number.

It is an amenable number.

644841 is a deficient number, since it is larger than the sum of its proper divisors (371559).

644841 is a wasteful number, since it uses less digits than its factorization.

644841 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 450 (or 441 counting only the distinct ones).

The product of its digits is 3072, while the sum is 27.

The square root of 644841 is about 803.0199250330. The cubic root of 644841 is about 86.3941257580.

It can be divided in two parts, 644 and 841, that added together give a triangular number (1485 = T₅₄).

The spelling of 644841 in words is "six hundred forty-four thousand, eight hundred forty-one".