206664391 has 2 divisors, whose sum is σ = 206664392. Its totient is φ = 206664390.

The previous prime is 206664323. The next prime is 206664413. The reversal of 206664391 is 193466602.

It is a happy number.

206664391 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 206664391 - 2²⁷ = 72446663 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 206664391.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (206664301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 103332195 + 103332196.

It is an arithmetic number, because the mean of its divisors is an integer number (103332196).

Almost surely, 2^206664391 is an apocalyptic number.

206664391 is a deficient number, since it is larger than the sum of its proper divisors (1).

206664391 is an equidigital number, since it uses as much as digits as its factorization.

206664391 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 46656, while the sum is 37.

The square root of 206664391 is about 14375.8266197113. The cubic root of 206664391 is about 591.2283047879.

The spelling of 206664391 in words is "two hundred six million, six hundred sixty-four thousand, three hundred ninety-one".