647666057 has 2 divisors, whose sum is σ = 647666058. Its totient is φ = 647666056.

The previous prime is 647666023. The next prime is 647666059. The reversal of 647666057 is 750666746.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 465308041 + 182358016 = 21571^2 + 13504^2 .

It is a cyclic number.

It is not a de Polignac number, because 647666057 - 2⁸ = 647665801 is a prime.

Together with 647666059, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (647666059) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323833028 + 323833029.

It is an arithmetic number, because the mean of its divisors is an integer number (323833029).

Almost surely, 2^647666057 is an apocalyptic number.

It is an amenable number.

647666057 is a deficient number, since it is larger than the sum of its proper divisors (1).

647666057 is an equidigital number, since it uses as much as digits as its factorization.

647666057 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1270080, while the sum is 47.

The square root of 647666057 is about 25449.2840174336. The cubic root of 647666057 is about 865.2010656700.

The spelling of 647666057 in words is "six hundred forty-seven million, six hundred sixty-six thousand, fifty-seven".