644839242 has 8 divisors (see below), whose sum is σ = 1289678496. Its totient is φ = 214946412.

The previous prime is 644839241. The next prime is 644839249. The reversal of 644839242 is 242938446.

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

644839242 is an admirable number.

It is a junction number, because it is equal to n+sod(n) for n = 644839194 and 644839203.

It is not an unprimeable number, because it can be changed into a prime (644839241) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 53736598 + ... + 53736609.

It is an arithmetic number, because the mean of its divisors is an integer number (161209812).

Almost surely, 2^644839242 is an apocalyptic number.

644839242 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.

644839242 is a wasteful number, since it uses less digits than its factorization.

644839242 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 107473212.

The product of its digits is 331776, while the sum is 42.

The square root of 644839242 is about 25393.6850811378. The cubic root of 644839242 is about 863.9404724720.

The spelling of 644839242 in words is "six hundred forty-four million, eight hundred thirty-nine thousand, two hundred forty-two".