645428256 has 192 divisors, whose sum is σ = 1978058880. Its totient is φ = 182108160.

The previous prime is 645428249. The next prime is 645428257. The reversal of 645428256 is 652824546.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (645428257) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2818350 + ... + 2818578.

It is an arithmetic number, because the mean of its divisors is an integer number (10302390).

Almost surely, 2^645428256 is an apocalyptic number.

645428256 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645428256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (989029440).

645428256 is an abundant number, since it is smaller than the sum of its proper divisors (1332630624).

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

645428256 is a wasteful number, since it uses less digits than its factorization.

645428256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 427 (or 419 counting only the distinct ones).

The product of its digits is 460800, while the sum is 42.

The square root of 645428256 is about 25405.2800811170. The cubic root of 645428256 is about 864.2034414620.

The spelling of 645428256 in words is "six hundred forty-five million, four hundred twenty-eight thousand, two hundred fifty-six".