645442056 has 192 divisors, whose sum is σ = 2069608320. Its totient is φ = 177914880.

The previous prime is 645442051. The next prime is 645442079. The reversal of 645442056 is 650244546.

645442056 is a `hidden beast` number, since 64 + 544 + 2 + 0 + 56 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 645442056.

It is not an unprimeable number, because it can be changed into a prime (645442051) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1949811 + ... + 1950141.

It is an arithmetic number, because the mean of its divisors is an integer number (10779210).

Almost surely, 2^645442056 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 645442056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1034804160).

645442056 is an abundant number, since it is smaller than the sum of its proper divisors (1424166264).

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

645442056 is a wasteful number, since it uses less digits than its factorization.

645442056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 476 (or 469 counting only the distinct ones).

The product of its (nonzero) digits is 115200, while the sum is 36.

The square root of 645442056 is about 25405.5516767497. The cubic root of 645442056 is about 864.2096006399.

The spelling of 645442056 in words is "six hundred forty-five million, four hundred forty-two thousand, fifty-six".