647171257 has 2 divisors, whose sum is σ = 647171258. Its totient is φ = 647171256.

The previous prime is 647171237. The next prime is 647171321. The reversal of 647171257 is 752171746.

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., 533194281 + 113976976 = 23091^2 + 10676^2 .

It is a cyclic number.

It is not a de Polignac number, because 647171257 - 2²³ = 638782649 is a prime.

It is not a weakly prime, because it can be changed into another prime (647171237) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323585628 + 323585629.

It is an arithmetic number, because the mean of its divisors is an integer number (323585629).

Almost surely, 2^647171257 is an apocalyptic number.

It is an amenable number.

647171257 is a deficient number, since it is larger than the sum of its proper divisors (1).

647171257 is an equidigital number, since it uses as much as digits as its factorization.

647171257 is an evil number, because the sum of its binary digits is even.

The product of its digits is 82320, while the sum is 40.

The square root of 647171257 is about 25439.5608649206. The cubic root of 647171257 is about 864.9806791769.

The spelling of 647171257 in words is "six hundred forty-seven million, one hundred seventy-one thousand, two hundred fifty-seven".