644402 has 16 divisors (see below), whose sum is σ = 1117152. Its totient is φ = 275520.

The previous prime is 644401. The next prime is 644411. The reversal of 644402 is 204446.

644402 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (644401) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 488 + ... + 1235.

It is an arithmetic number, because the mean of its divisors is an integer number (69822).

2⁶⁴⁴⁴⁰² is an apocalyptic number.

644402 is a deficient number, since it is larger than the sum of its proper divisors (472750).

644402 is a wasteful number, since it uses less digits than its factorization.

644402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1753.

The product of its (nonzero) digits is 768, while the sum is 20.

The square root of 644402 is about 802.7465353398. The cubic root of 644402 is about 86.3745159466.

Adding to 644402 its reverse (204446), we get a palindrome (848848).

The spelling of 644402 in words is "six hundred forty-four thousand, four hundred two".