645822 has 12 divisors (see below), whose sum is σ = 1399320. Its totient is φ = 215268.

The previous prime is 645803. The next prime is 645833. The reversal of 645822 is 228546.

It is a congruent number.

It is an unprimeable number.

645822 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 17922 + ... + 17957.

It is an arithmetic number, because the mean of its divisors is an integer number (116610).

2⁶⁴⁵⁸²² is an apocalyptic number.

645822 is an abundant number, since it is smaller than the sum of its proper divisors (753498).

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

645822 is a wasteful number, since it uses less digits than its factorization.

645822 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35887 (or 35884 counting only the distinct ones).

The product of its digits is 3840, while the sum is 27.

The square root of 645822 is about 803.6305121136. The cubic root of 645822 is about 86.4379141728.

It can be divided in two parts, 64 and 5822, that added together give a triangular number (5886 = T₁₀₈).

The spelling of 645822 in words is "six hundred forty-five thousand, eight hundred twenty-two".