645812 has 6 divisors (see below), whose sum is σ = 1130178. Its totient is φ = 322904.

The previous prime is 645803. The next prime is 645833. The reversal of 645812 is 218546.

It can be written as a sum of positive squares in only one way, i.e., 630436 + 15376 = 794^2 + 124^2 .

It is a nialpdrome in base 15.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 645812.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80723 + ... + 80730.

It is an arithmetic number, because the mean of its divisors is an integer number (188363).

2⁶⁴⁵⁸¹² is an apocalyptic number.

It is an amenable number.

645812 is a deficient number, since it is larger than the sum of its proper divisors (484366).

645812 is a wasteful number, since it uses less digits than its factorization.

645812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161457 (or 161455 counting only the distinct ones).

The product of its digits is 1920, while the sum is 26.

The square root of 645812 is about 803.6242903248. The cubic root of 645812 is about 86.4374680315.

The spelling of 645812 in words is "six hundred forty-five thousand, eight hundred twelve".