644123252 has 12 divisors (see below), whose sum is σ = 1133444676. Its totient is φ = 320281920.

The previous prime is 644123213. The next prime is 644123279. The reversal of 644123252 is 252321446.

It can be written as a sum of positive squares in 2 ways, for example, as 90744676 + 553378576 = 9526^2 + 23524^2 .

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 444113 + ... + 445560.

It is an arithmetic number, because the mean of its divisors is an integer number (94453723).

Almost surely, 2^644123252 is an apocalyptic number.

It is an amenable number.

644123252 is a deficient number, since it is larger than the sum of its proper divisors (489321424).

644123252 is a wasteful number, since it uses less digits than its factorization.

644123252 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 889858 (or 889856 counting only the distinct ones).

The product of its digits is 11520, while the sum is 29.

The square root of 644123252 is about 25379.5833693148. The cubic root of 644123252 is about 863.6205985243.

Adding to 644123252 its reverse (252321446), we get a palindrome (896444698).

The spelling of 644123252 in words is "six hundred forty-four million, one hundred twenty-three thousand, two hundred fifty-two".