644132 has 6 divisors (see below), whose sum is σ = 1127238. Its totient is φ = 322064.

The previous prime is 644131. The next prime is 644141. The reversal of 644132 is 231446.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 556516 + 87616 = 746^2 + 296^2 .

It is not an unprimeable number, because it can be changed into a prime (644131) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80513 + ... + 80520.

It is an arithmetic number, because the mean of its divisors is an integer number (187873).

2⁶⁴⁴¹³² is an apocalyptic number.

It is an amenable number.

644132 is a deficient number, since it is larger than the sum of its proper divisors (483106).

644132 is a wasteful number, since it uses less digits than its factorization.

644132 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 161037 (or 161035 counting only the distinct ones).

The product of its digits is 576, while the sum is 20.

The square root of 644132 is about 802.5783450854. The cubic root of 644132 is about 86.3624508189.

Adding to 644132 its reverse (231446), we get a palindrome (875578).

Subtracting from 644132 its reverse (231446), we obtain a triangular number (412686 = T₉₀₈).

The spelling of 644132 in words is "six hundred forty-four thousand, one hundred thirty-two".