644777842 has 16 divisors (see below), whose sum is σ = 984401280. Its totient is φ = 316653552.

The previous prime is 644777831. The next prime is 644777843. The reversal of 644777842 is 248777446.

It is not an unprimeable number, because it can be changed into a prime (644777843) 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, 269383 + ... + 271765.

It is an arithmetic number, because the mean of its divisors is an integer number (61525080).

Almost surely, 2^644777842 is an apocalyptic number.

644777842 is a deficient number, since it is larger than the sum of its proper divisors (339623438).

644777842 is a wasteful number, since it uses less digits than its factorization.

644777842 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4737.

The product of its digits is 2107392, while the sum is 49.

The square root of 644777842 is about 25392.4760903698. The cubic root of 644777842 is about 863.9130508423.

The spelling of 644777842 in words is "six hundred forty-four million, seven hundred seventy-seven thousand, eight hundred forty-two".