644775667 has 2 divisors, whose sum is σ = 644775668. Its totient is φ = 644775666.

The previous prime is 644775631. The next prime is 644775679. The reversal of 644775667 is 766577446.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 644775667 - 2¹⁵ = 644742899 is a prime.

It is not a weakly prime, because it can be changed into another prime (644776667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322387833 + 322387834.

It is an arithmetic number, because the mean of its divisors is an integer number (322387834).

Almost surely, 2^644775667 is an apocalyptic number.

644775667 is a deficient number, since it is larger than the sum of its proper divisors (1).

644775667 is an equidigital number, since it uses as much as digits as its factorization.

644775667 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5927040, while the sum is 52.

The square root of 644775667 is about 25392.4332626867. The cubic root of 644775667 is about 863.9120794416.

The spelling of 644775667 in words is "six hundred forty-four million, seven hundred seventy-five thousand, six hundred sixty-seven".