645206904 has 64 divisors (see below), whose sum is σ = 1814976000. Its totient is φ = 212340960.

The previous prime is 645206893. The next prime is 645206909. The reversal of 645206904 is 409602546.

645206904 is a `hidden beast` number, since 645 + 2 + 0 + 6 + 9 + 0 + 4 = 666.

645206904 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645206909) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1842 + ... + 35969.

It is an arithmetic number, because the mean of its divisors is an integer number (28359000).

Almost surely, 2^645206904 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 645206904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (907488000).

645206904 is an abundant number, since it is smaller than the sum of its proper divisors (1169769096).

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

645206904 is a wasteful number, since it uses less digits than its factorization.

645206904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37905 (or 37895 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

The square root of 645206904 is about 25400.9232903058. The cubic root of 645206904 is about 864.1046362471.

The spelling of 645206904 in words is "six hundred forty-five million, two hundred six thousand, nine hundred four".