644394967 has 2 divisors, whose sum is σ = 644394968. Its totient is φ = 644394966.

The previous prime is 644394953. The next prime is 644394983. The reversal of 644394967 is 769493446.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 644394967 - 2¹⁹ = 643870679 is a prime.

It is a super-5 number, since 5×644394967⁵ (a number of 45 digits) contains 55555 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644394067) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322197483 + 322197484.

It is an arithmetic number, because the mean of its divisors is an integer number (322197484).

Almost surely, 2^644394967 is an apocalyptic number.

644394967 is a deficient number, since it is larger than the sum of its proper divisors (1).

644394967 is an equidigital number, since it uses as much as digits as its factorization.

644394967 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3919104, while the sum is 52.

The square root of 644394967 is about 25384.9358281639. The cubic root of 644394967 is about 863.7420171513.

The spelling of 644394967 in words is "six hundred forty-four million, three hundred ninety-four thousand, nine hundred sixty-seven".