644443797 has 8 divisors (see below), whose sum is σ = 859921056. Its totient is φ = 429297872.

The previous prime is 644443777. The next prime is 644443817. The reversal of 644443797 is 797344446.

It is an interprime number because it is at equal distance from previous prime (644443777) and next prime (644443817).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 644443797 - 2⁷ = 644443669 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644443777) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 78258 + ... + 86099.

It is an arithmetic number, because the mean of its divisors is an integer number (107490132).

Almost surely, 2^644443797 is an apocalyptic number.

It is an amenable number.

644443797 is a deficient number, since it is larger than the sum of its proper divisors (215477259).

644443797 is a wasteful number, since it uses less digits than its factorization.

644443797 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165667.

The product of its digits is 2032128, while the sum is 48.

The square root of 644443797 is about 25385.8976008334. The cubic root of 644443797 is about 863.7638337181.

The spelling of 644443797 in words is "six hundred forty-four million, four hundred forty-three thousand, seven hundred ninety-seven".