645800823 has 16 divisors (see below), whose sum is σ = 1007097600. Its totient is φ = 407873880.

The previous prime is 645800819. The next prime is 645800893. The reversal of 645800823 is 328008546.

645800823 is a `hidden beast` number, since 645 + 8 + 0 + 0 + 8 + 2 + 3 = 666.

It is not a de Polignac number, because 645800823 - 2² = 645800819 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645800893) 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, 628923 + ... + 629948.

It is an arithmetic number, because the mean of its divisors is an integer number (62943600).

Almost surely, 2^645800823 is an apocalyptic number.

645800823 is a deficient number, since it is larger than the sum of its proper divisors (361296777).

645800823 is a wasteful number, since it uses less digits than its factorization.

645800823 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1258899 (or 1258893 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 36.

The square root of 645800823 is about 25412.6114950825. The cubic root of 645800823 is about 864.3696937389.

The spelling of 645800823 in words is "six hundred forty-five million, eight hundred thousand, eight hundred twenty-three".