644432 has 10 divisors (see below), whose sum is σ = 1248618. Its totient is φ = 322208.

The previous prime is 644431. The next prime is 644443. The reversal of 644432 is 234446.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 633616 + 10816 = 796^2 + 104^2 .

It is a plaindrome in base 14.

It is a nialpdrome in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 644398 and 644407.

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 polite number, since it can be written as a sum of consecutive naturals, namely, 20123 + ... + 20154.

2⁶⁴⁴⁴³² is an apocalyptic number.

It is an amenable number.

644432 is a deficient number, since it is larger than the sum of its proper divisors (604186).

644432 is a wasteful number, since it uses less digits than its factorization.

644432 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40285 (or 40279 counting only the distinct ones).

The product of its digits is 2304, while the sum is 23.

The square root of 644432 is about 802.7652209706. The cubic root of 644432 is about 86.3758563083.

Adding to 644432 its reverse (234446), we get a palindrome (878878).

The spelling of 644432 in words is "six hundred forty-four thousand, four hundred thirty-two".