646665847 has 2 divisors, whose sum is σ = 646665848. Its totient is φ = 646665846.

The previous prime is 646665739. The next prime is 646665853. The reversal of 646665847 is 748566646.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 646665847 - 2²³ = 638277239 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 646665794 and 646665803.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (646663847) 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, 323332923 + 323332924.

It is an arithmetic number, because the mean of its divisors is an integer number (323332924).

Almost surely, 2^646665847 is an apocalyptic number.

646665847 is a deficient number, since it is larger than the sum of its proper divisors (1).

646665847 is an equidigital number, since it uses as much as digits as its factorization.

646665847 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5806080, while the sum is 52.

The square root of 646665847 is about 25429.6253806461. The cubic root of 646665847 is about 864.7554509328.

The spelling of 646665847 in words is "six hundred forty-six million, six hundred sixty-five thousand, eight hundred forty-seven".