644144357 has 2 divisors, whose sum is σ = 644144358. Its totient is φ = 644144356.

The previous prime is 644144341. The next prime is 644144363. The reversal of 644144357 is 753441446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 611127841 + 33016516 = 24721^2 + 5746^2 .

It is a cyclic number.

It is not a de Polignac number, because 644144357 - 2⁴ = 644144341 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 644144357.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644144377) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322072178 + 322072179.

It is an arithmetic number, because the mean of its divisors is an integer number (322072179).

Almost surely, 2^644144357 is an apocalyptic number.

It is an amenable number.

644144357 is a deficient number, since it is larger than the sum of its proper divisors (1).

644144357 is an equidigital number, since it uses as much as digits as its factorization.

644144357 is an evil number, because the sum of its binary digits is even.

The product of its digits is 161280, while the sum is 38.

The square root of 644144357 is about 25379.9991528763. Note that the first 3 decimals coincide. The cubic root of 644144357 is about 863.6300307324.

The spelling of 644144357 in words is "six hundred forty-four million, one hundred forty-four thousand, three hundred fifty-seven".