644443867 has 2 divisors, whose sum is σ = 644443868. Its totient is φ = 644443866.

The previous prime is 644443823. The next prime is 644443873. The reversal of 644443867 is 768344446.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 644443867 - 2¹⁵ = 644411099 is a prime.

It is not a weakly prime, because it can be changed into another prime (644443817) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322221933 + 322221934.

It is an arithmetic number, because the mean of its divisors is an integer number (322221934).

Almost surely, 2^644443867 is an apocalyptic number.

644443867 is a deficient number, since it is larger than the sum of its proper divisors (1).

644443867 is an equidigital number, since it uses as much as digits as its factorization.

644443867 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1548288, while the sum is 46.

The square root of 644443867 is about 25385.8989795516. The cubic root of 644443867 is about 863.7638649923.

The spelling of 644443867 in words is "six hundred forty-four million, four hundred forty-three thousand, eight hundred sixty-seven".