645881472 has 128 divisors (see below), whose sum is σ = 1958155200. Its totient is φ = 209433600.

The previous prime is 645881461. The next prime is 645881491. The reversal of 645881472 is 274188546.

645881472 is a `hidden beast` number, since 64 + 588 + 1 + 4 + 7 + 2 = 666.

It is a tau number, because it is divible by the number of its divisors (128).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 125347 + ... + 130397.

Almost surely, 2^645881472 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 645881472, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (979077600).

645881472 is an abundant number, since it is smaller than the sum of its proper divisors (1312273728).

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

645881472 is a wasteful number, since it uses less digits than its factorization.

645881472 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5111 (or 5093 counting only the distinct ones).

The product of its digits is 430080, while the sum is 45.

The square root of 645881472 is about 25414.1982364189. The cubic root of 645881472 is about 864.4056736919.

The spelling of 645881472 in words is "six hundred forty-five million, eight hundred eighty-one thousand, four hundred seventy-two".