645218857 has 2 divisors, whose sum is σ = 645218858. Its totient is φ = 645218856.

The previous prime is 645218807. The next prime is 645218863. The reversal of 645218857 is 758812546.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 620458281 + 24760576 = 24909^2 + 4976^2 .

It is a cyclic number.

It is not a de Polignac number, because 645218857 - 2⁷ = 645218729 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (645218807) 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 as a sum of consecutive naturals, namely, 322609428 + 322609429.

It is an arithmetic number, because the mean of its divisors is an integer number (322609429).

Almost surely, 2^645218857 is an apocalyptic number.

It is an amenable number.

645218857 is a deficient number, since it is larger than the sum of its proper divisors (1).

645218857 is an equidigital number, since it uses as much as digits as its factorization.

645218857 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 537600, while the sum is 46.

The square root of 645218857 is about 25401.1585759390. The cubic root of 645218857 is about 864.1099723023.

The spelling of 645218857 in words is "six hundred forty-five million, two hundred eighteen thousand, eight hundred fifty-seven".