645173244 has 36 divisors (see below), whose sum is σ = 1631664216. Its totient is φ = 214951008.

The previous prime is 645173219. The next prime is 645173281. The reversal of 645173244 is 442371546.

645173244 is a `hidden beast` number, since 645 + 1 + 7 + 3 + 2 + 4 + 4 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

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

It is a junction number, because it is equal to n+sod(n) for n = 645173199 and 645173208.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 108082 + ... + 113894.

It is an arithmetic number, because the mean of its divisors is an integer number (45324006).

Almost surely, 2^645173244 is an apocalyptic number.

It is an amenable number.

645173244 is an abundant number, since it is smaller than the sum of its proper divisors (986490972).

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

645173244 is a wasteful number, since it uses less digits than its factorization.

645173244 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8906 (or 8901 counting only the distinct ones).

The product of its digits is 80640, while the sum is 36.

The square root of 645173244 is about 25400.2607073235. The cubic root of 645173244 is about 864.0896094044.

It can be divided in two parts, 645 and 173244, that added together give a square (173889 = 417²).

The spelling of 645173244 in words is "six hundred forty-five million, one hundred seventy-three thousand, two hundred forty-four".