645863291 has 2 divisors, whose sum is σ = 645863292. Its totient is φ = 645863290.

The previous prime is 645863287. The next prime is 645863329. The reversal of 645863291 is 192368546.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 645863291 - 2² = 645863287 is a prime.

It is a super-2 number, since 2×645863291² = 834278781322701362, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (645863261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322931645 + 322931646.

It is an arithmetic number, because the mean of its divisors is an integer number (322931646).

Almost surely, 2^645863291 is an apocalyptic number.

645863291 is a deficient number, since it is larger than the sum of its proper divisors (1).

645863291 is an equidigital number, since it uses as much as digits as its factorization.

645863291 is an evil number, because the sum of its binary digits is even.

The product of its digits is 311040, while the sum is 44.

The square root of 645863291 is about 25413.8405401466. The cubic root of 645863291 is about 864.3975628605.

The spelling of 645863291 in words is "six hundred forty-five million, eight hundred sixty-three thousand, two hundred ninety-one".