646006391 has 2 divisors, whose sum is σ = 646006392. Its totient is φ = 646006390.

The previous prime is 646006379. The next prime is 646006433. The reversal of 646006391 is 193600646.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-646006391 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 (646006891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323003195 + 323003196.

It is an arithmetic number, because the mean of its divisors is an integer number (323003196).

Almost surely, 2^646006391 is an apocalyptic number.

646006391 is a deficient number, since it is larger than the sum of its proper divisors (1).

646006391 is an equidigital number, since it uses as much as digits as its factorization.

646006391 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23328, while the sum is 35.

The square root of 646006391 is about 25416.6557792326. The cubic root of 646006391 is about 864.4613979159.

The spelling of 646006391 in words is "six hundred forty-six million, six thousand, three hundred ninety-one".