644093641 has 9 divisors (see below), whose sum is σ = 661254663. Its totient is φ = 627368880.

The previous prime is 644093629. The next prime is 644093663. The reversal of 644093641 is 146390446.

The square root of 644093641 is 25379.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 31036041 + 613057600 = 5571^2 + 24760^2 .

It is not a de Polignac number, because 644093641 - 2¹⁵ = 644060873 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 644093641.

It is not an unprimeable number, because it can be changed into a prime (644093041) by changing a digit.

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 8 ways as a sum of consecutive naturals, for example, 1040230 + ... + 1040848.

Almost surely, 2^644093641 is an apocalyptic number.

644093641 is the 25379-th square number.

644093641 is the 12690-th centered octagonal number.

It is an amenable number.

644093641 is a deficient number, since it is larger than the sum of its proper divisors (17161022).

644093641 is an frugal number, since it uses more digits than its factorization.

644093641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1320 (or 660 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 37.

The cubic root of 644093641 is about 863.6073644828.

The spelling of 644093641 in words is "six hundred forty-four million, ninety-three thousand, six hundred forty-one".