646974091 has 2 divisors, whose sum is σ = 646974092. Its totient is φ = 646974090.

The previous prime is 646974077. The next prime is 646974101. The reversal of 646974091 is 190479646.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 646974091 - 2⁵ = 646974059 is a prime.

It is not a weakly prime, because it can be changed into another prime (646974011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323487045 + 323487046.

It is an arithmetic number, because the mean of its divisors is an integer number (323487046).

Almost surely, 2^646974091 is an apocalyptic number.

646974091 is a deficient number, since it is larger than the sum of its proper divisors (1).

646974091 is an equidigital number, since it uses as much as digits as its factorization.

646974091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 326592, while the sum is 46.

The square root of 646974091 is about 25435.6853849076. The cubic root of 646974091 is about 864.8928291161.

The spelling of 646974091 in words is "six hundred forty-six million, nine hundred seventy-four thousand, ninety-one".