645422656 has 56 divisors (see below), whose sum is σ = 1319076864. Its totient is φ = 313144320.

The previous prime is 645422633. The next prime is 645422671. The reversal of 645422656 is 656224546.

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 7 ways as a sum of consecutive naturals, for example, 584601 + ... + 585703.

It is an arithmetic number, because the mean of its divisors is an integer number (23554944).

Almost surely, 2^645422656 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 645422656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (659538432).

645422656 is an abundant number, since it is smaller than the sum of its proper divisors (673654208).

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

645422656 is a wasteful number, since it uses less digits than its factorization.

645422656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1379 (or 1369 counting only the distinct ones).

The product of its digits is 345600, while the sum is 40.

The square root of 645422656 is about 25405.1698675683. The cubic root of 645422656 is about 864.2009420604.

The spelling of 645422656 in words is "six hundred forty-five million, four hundred twenty-two thousand, six hundred fifty-six".