644106253 has 4 divisors (see below), whose sum is σ = 736121440. Its totient is φ = 552091068.

The previous prime is 644106247. The next prime is 644106257. The reversal of 644106253 is 352601446.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644106253 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644106257) by changing a digit.

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 in 3 ways as a sum of consecutive naturals, for example, 46007583 + ... + 46007596.

It is an arithmetic number, because the mean of its divisors is an integer number (184030360).

Almost surely, 2^644106253 is an apocalyptic number.

It is an amenable number.

644106253 is a deficient number, since it is larger than the sum of its proper divisors (92015187).

644106253 is an equidigital number, since it uses as much as digits as its factorization.

644106253 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92015186.

The product of its (nonzero) digits is 17280, while the sum is 31.

The square root of 644106253 is about 25379.2484719308. The cubic root of 644106253 is about 863.6130012124.

Adding to 644106253 its reverse (352601446), we get a palindrome (996707699).

The spelling of 644106253 in words is "six hundred forty-four million, one hundred six thousand, two hundred fifty-three".