644093919 has 12 divisors (see below), whose sum is σ = 1063266256. Its totient is φ = 368053632.

The previous prime is 644093911. The next prime is 644093927. The reversal of 644093919 is 919390446.

It is an interprime number because it is at equal distance from previous prime (644093911) and next prime (644093927).

It is not a de Polignac number, because 644093919 - 2³ = 644093911 is a prime.

It is a super-2 number, since 2×644093919² = 829713952985557122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644093911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5111794 + ... + 5111919.

Almost surely, 2^644093919 is an apocalyptic number.

644093919 is a deficient number, since it is larger than the sum of its proper divisors (419172337).

644093919 is a wasteful number, since it uses less digits than its factorization.

644093919 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10223726 (or 10223723 counting only the distinct ones).

The product of its (nonzero) digits is 209952, while the sum is 45.

The square root of 644093919 is about 25379.0054769686. The cubic root of 644093919 is about 863.6074887312.

The spelling of 644093919 in words is "six hundred forty-four million, ninety-three thousand, nine hundred nineteen".