645739189 has 2 divisors, whose sum is σ = 645739190. Its totient is φ = 645739188.

The previous prime is 645739183. The next prime is 645739219. The reversal of 645739189 is 981937546.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 644398225 + 1340964 = 25385^2 + 1158^2 .

It is a cyclic number.

It is not a de Polignac number, because 645739189 - 2²⁵ = 612184757 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645739183) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322869594 + 322869595.

It is an arithmetic number, because the mean of its divisors is an integer number (322869595).

Almost surely, 2^645739189 is an apocalyptic number.

It is an amenable number.

645739189 is a deficient number, since it is larger than the sum of its proper divisors (1).

645739189 is an equidigital number, since it uses as much as digits as its factorization.

645739189 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1632960, while the sum is 52.

The square root of 645739189 is about 25411.3988005383. The cubic root of 645739189 is about 864.3421949319.

The spelling of 645739189 in words is "six hundred forty-five million, seven hundred thirty-nine thousand, one hundred eighty-nine".