644522 has 4 divisors (see below), whose sum is σ = 966786. Its totient is φ = 322260.

The previous prime is 644519. The next prime is 644531. The reversal of 644522 is 225446.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 561001 + 83521 = 749^2 + 289^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 161129 + ... + 161132.

2⁶⁴⁴⁵²² is an apocalyptic number.

644522 is a deficient number, since it is larger than the sum of its proper divisors (322264).

644522 is a wasteful number, since it uses less digits than its factorization.

644522 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 322263.

The product of its digits is 1920, while the sum is 23.

The square root of 644522 is about 802.8212752537. The cubic root of 644522 is about 86.3798771438.

Adding to 644522 its reverse (225446), we get a palindrome (869968).

The spelling of 644522 in words is "six hundred forty-four thousand, five hundred twenty-two".