644733 has 8 divisors (see below), whose sum is σ = 955200. Its totient is φ = 429804.

The previous prime is 644731. The next prime is 644747. The reversal of 644733 is 337446.

It is not a de Polignac number, because 644733 - 2¹ = 644731 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 23879 = 644733 / (6 + 4 + 4 + 7 + 3 + 3).

It is a d-powerful number, because it can be written as 6⁶ + 4⁵ + 7² + 4⁸ + 3³ + 3¹² .

644733 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 644697 and 644706.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 644733.

It is not an unprimeable number, because it can be changed into a prime (644731) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11913 + ... + 11966.

It is an arithmetic number, because the mean of its divisors is an integer number (119400).

2⁶⁴⁴⁷³³ is an apocalyptic number.

It is an amenable number.

644733 is a deficient number, since it is larger than the sum of its proper divisors (310467).

644733 is a wasteful number, since it uses less digits than its factorization.

644733 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23888 (or 23882 counting only the distinct ones).

The product of its digits is 6048, while the sum is 27.

The square root of 644733 is about 802.9526760650. The cubic root of 644733 is about 86.3893023021.

The spelling of 644733 in words is "six hundred forty-four thousand, seven hundred thirty-three".