644377 has 2 divisors, whose sum is σ = 644378. Its totient is φ = 644376.

The previous prime is 644363. The next prime is 644381. The reversal of 644377 is 773446.

644377 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 can be written as a sum of positive squares in only one way, i.e., 335241 + 309136 = 579^2 + 556^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644377 is a prime.

It is a d-powerful number, because it can be written as 6² + 4⁹ + 3 + 4⁹ + 7⁴ + 7⁶ .

It is not a weakly prime, because it can be changed into another prime (644327) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322188 + 322189.

It is an arithmetic number, because the mean of its divisors is an integer number (322189).

2⁶⁴⁴³⁷⁷ is an apocalyptic number.

It is an amenable number.

644377 is a deficient number, since it is larger than the sum of its proper divisors (1).

644377 is an equidigital number, since it uses as much as digits as its factorization.

644377 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14112, while the sum is 31.

The square root of 644377 is about 802.7309636485. The cubic root of 644377 is about 86.3733989468.

The spelling of 644377 in words is "six hundred forty-four thousand, three hundred seventy-seven".