644263842 has 8 divisors (see below), whose sum is σ = 1288527696. Its totient is φ = 214754612.

The previous prime is 644263831. The next prime is 644263853. The reversal of 644263842 is 248362446.

It is an interprime number because it is at equal distance from previous prime (644263831) and next prime (644263853).

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

644263842 is an admirable number.

It is a self number, because there is not a number n which added to its sum of digits gives 644263842.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 53688648 + ... + 53688659.

It is an arithmetic number, because the mean of its divisors is an integer number (161065962).

Almost surely, 2^644263842 is an apocalyptic number.

644263842 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644263842 is a wasteful number, since it uses less digits than its factorization.

644263842 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 107377312.

The product of its digits is 221184, while the sum is 39.

The square root of 644263842 is about 25382.3529642151. The cubic root of 644263842 is about 863.6834268660.

The spelling of 644263842 in words is "six hundred forty-four million, two hundred sixty-three thousand, eight hundred forty-two".