645739219 has 2 divisors, whose sum is σ = 645739220. Its totient is φ = 645739218.

The previous prime is 645739189. The next prime is 645739231. The reversal of 645739219 is 912937546.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 645739219 - 2⁷ = 645739091 is a prime.

It is a super-2 number, since 2×645739219² = 833958277909459922, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (645739319) 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, 322869609 + 322869610.

It is an arithmetic number, because the mean of its divisors is an integer number (322869610).

Almost surely, 2^645739219 is an apocalyptic number.

645739219 is a deficient number, since it is larger than the sum of its proper divisors (1).

645739219 is an equidigital number, since it uses as much as digits as its factorization.

645739219 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 408240, while the sum is 46.

The square root of 645739219 is about 25411.3993908246. The cubic root of 645739219 is about 864.3422083172.

The spelling of 645739219 in words is "six hundred forty-five million, seven hundred thirty-nine thousand, two hundred nineteen".