645320873 has 2 divisors, whose sum is σ = 645320874. Its totient is φ = 645320872.

The previous prime is 645320869. The next prime is 645320887. The reversal of 645320873 is 378023546.

645320873 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 645312409 + 8464 = 25403^2 + 92^2 .

It is a cyclic number.

It is not a de Polignac number, because 645320873 - 2² = 645320869 is a prime.

It is not a weakly prime, because it can be changed into another prime (645323873) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322660436 + 322660437.

It is an arithmetic number, because the mean of its divisors is an integer number (322660437).

Almost surely, 2^645320873 is an apocalyptic number.

It is an amenable number.

645320873 is a deficient number, since it is larger than the sum of its proper divisors (1).

645320873 is an equidigital number, since it uses as much as digits as its factorization.

645320873 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 120960, while the sum is 38.

The square root of 645320873 is about 25403.1665939504. The cubic root of 645320873 is about 864.1555115775.

The spelling of 645320873 in words is "six hundred forty-five million, three hundred twenty thousand, eight hundred seventy-three".