645802020 has 72 divisors (see below), whose sum is σ = 2062045440. Its totient is φ = 163149120.

The previous prime is 645802009. The next prime is 645802021. The reversal of 645802020 is 20208546.

645802020 is a `hidden beast` number, since 6 + 458 + 0 + 202 + 0 = 666.

It is not an unprimeable number, because it can be changed into a prime (645802021) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 90996 + ... + 97835.

It is an arithmetic number, because the mean of its divisors is an integer number (28639520).

Almost surely, 2^645802020 is an apocalyptic number.

645802020 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

645802020 is an abundant number, since it is smaller than the sum of its proper divisors (1416243420).

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

645802020 is a wasteful number, since it uses less digits than its factorization.

645802020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 188865 (or 188860 counting only the distinct ones).

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

The square root of 645802020 is about 25412.6350463701. The cubic root of 645802020 is about 864.3702277786.

The spelling of 645802020 in words is "six hundred forty-five million, eight hundred two thousand, twenty".