642804656 has 80 divisors (see below), whose sum is σ = 1419075840. Its totient is φ = 279624960.

The previous prime is 642804611. The next prime is 642804671. The reversal of 642804656 is 656408246.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1228811 + ... + 1229333.

It is an arithmetic number, because the mean of its divisors is an integer number (17738448).

Almost surely, 2^642804656 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 642804656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (709537920).

642804656 is an abundant number, since it is smaller than the sum of its proper divisors (776271184).

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

642804656 is a wasteful number, since it uses less digits than its factorization.

642804656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 874 (or 868 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 41.

The square root of 642804656 is about 25353.5925659462. The cubic root of 642804656 is about 863.0308849815.

The spelling of 642804656 in words is "six hundred forty-two million, eight hundred four thousand, six hundred fifty-six".