644959985 has 8 divisors (see below), whose sum is σ = 774513600. Its totient is φ = 515593584.

The previous prime is 644959961. The next prime is 644959999. The reversal of 644959985 is 589959446.

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 644959985 - 2⁸ = 644959729 is a prime.

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, 39107 + ... + 53096.

It is an arithmetic number, because the mean of its divisors is an integer number (96814200).

Almost surely, 2^644959985 is an apocalyptic number.

It is an amenable number.

644959985 is a deficient number, since it is larger than the sum of its proper divisors (129553615).

644959985 is a wasteful number, since it uses less digits than its factorization.

644959985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 93607.

The product of its digits is 13996800, while the sum is 59.

The square root of 644959985 is about 25396.0623916386. The cubic root of 644959985 is about 863.9943919853.

The spelling of 644959985 in words is "six hundred forty-four million, nine hundred fifty-nine thousand, nine hundred eighty-five".