644819612 has 24 divisors (see below), whose sum is σ = 1136686320. Its totient is φ = 320060160.

The previous prime is 644819603. The next prime is 644819621. The reversal of 644819612 is 216918446.

It is an interprime number because it is at equal distance from previous prime (644819603) and next prime (644819621).

It is a super-3 number, since 3×644819612³ (a number of 27 digits) contains 333 as substring.

It is a Smith number, since the sum of its digits (41) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 644819612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 638564 + ... + 639572.

It is an arithmetic number, because the mean of its divisors is an integer number (47361930).

Almost surely, 2^644819612 is an apocalyptic number.

It is an amenable number.

644819612 is a deficient number, since it is larger than the sum of its proper divisors (491866708).

644819612 is a wasteful number, since it uses less digits than its factorization.

644819612 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2021 (or 2019 counting only the distinct ones).

The product of its digits is 82944, while the sum is 41.

The square root of 644819612 is about 25393.2985647789. The cubic root of 644819612 is about 863.9317057787.

The spelling of 644819612 in words is "six hundred forty-four million, eight hundred nineteen thousand, six hundred twelve".