644791085 has 16 divisors (see below), whose sum is σ = 809326080. Its totient is φ = 492222720.

The previous prime is 644791031. The next prime is 644791097. The reversal of 644791085 is 580197446.

It is not a de Polignac number, because 644791085 - 2⁸ = 644790829 is a prime.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 43061 + ... + 56069.

It is an arithmetic number, because the mean of its divisors is an integer number (50582880).

Almost surely, 2^644791085 is an apocalyptic number.

It is an amenable number.

644791085 is a deficient number, since it is larger than the sum of its proper divisors (164534995).

644791085 is a wasteful number, since it uses less digits than its factorization.

644791085 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13468.

The product of its (nonzero) digits is 241920, while the sum is 44.

The square root of 644791085 is about 25392.7368552506. The cubic root of 644791085 is about 863.9189653974.

The spelling of 644791085 in words is "six hundred forty-four million, seven hundred ninety-one thousand, eighty-five".