646122391 has 2 divisors, whose sum is σ = 646122392. Its totient is φ = 646122390.

The previous prime is 646122377. The next prime is 646122401. The reversal of 646122391 is 193221646.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 646122391 - 2⁵ = 646122359 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (646122091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323061195 + 323061196.

It is an arithmetic number, because the mean of its divisors is an integer number (323061196).

Almost surely, 2^646122391 is an apocalyptic number.

646122391 is a deficient number, since it is larger than the sum of its proper divisors (1).

646122391 is an equidigital number, since it uses as much as digits as its factorization.

646122391 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15552, while the sum is 34.

The square root of 646122391 is about 25418.9376449922. The cubic root of 646122391 is about 864.5131370948.

The spelling of 646122391 in words is "six hundred forty-six million, one hundred twenty-two thousand, three hundred ninety-one".