642440256 has 56 divisors (see below), whose sum is σ = 1714890144. Its totient is φ = 212244480.

The previous prime is 642440231. The next prime is 642440263. The reversal of 642440256 is 652044246.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6891 + ... + 36501.

Almost surely, 2^642440256 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 642440256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (857445072).

642440256 is an abundant number, since it is smaller than the sum of its proper divisors (1072449888).

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

642440256 is a wasteful number, since it uses less digits than its factorization.

642440256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29739 (or 29729 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 33.

The square root of 642440256 is about 25346.4051889020. The cubic root of 642440256 is about 862.8677727529.

The spelling of 642440256 in words is "six hundred forty-two million, four hundred forty thousand, two hundred fifty-six".