644291 has 2 divisors, whose sum is σ = 644292. Its totient is φ = 644290.

The previous prime is 644261. The next prime is 644297. The reversal of 644291 is 192446.

644291 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 644291 - 2⁶ = 644227 is a prime.

It is a super-2 number, since 2×644291² = 830221785362, which contains 22 as substring.

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 644291.

It is not a weakly prime, because it can be changed into another prime (644297) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322145 + 322146.

It is an arithmetic number, because the mean of its divisors is an integer number (322146).

2⁶⁴⁴²⁹¹ is an apocalyptic number.

644291 is a deficient number, since it is larger than the sum of its proper divisors (1).

644291 is an equidigital number, since it uses as much as digits as its factorization.

644291 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1728, while the sum is 26.

The square root of 644291 is about 802.6773947234. The cubic root of 644291 is about 86.3695562466.

The spelling of 644291 in words is "six hundred forty-four thousand, two hundred ninety-one".