646405951 has 2 divisors, whose sum is σ = 646405952. Its totient is φ = 646405950.

The previous prime is 646405933. The next prime is 646405957. The reversal of 646405951 is 159504646.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 646405951 - 2⁹ = 646405439 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (646405957) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323202975 + 323202976.

It is an arithmetic number, because the mean of its divisors is an integer number (323202976).

Almost surely, 2^646405951 is an apocalyptic number.

646405951 is a deficient number, since it is larger than the sum of its proper divisors (1).

646405951 is an equidigital number, since it uses as much as digits as its factorization.

646405951 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 129600, while the sum is 40.

The square root of 646405951 is about 25424.5147642979. The cubic root of 646405951 is about 864.6395865601.

The spelling of 646405951 in words is "six hundred forty-six million, four hundred five thousand, nine hundred fifty-one".