206669989 has 2 divisors, whose sum is σ = 206669990. Its totient is φ = 206669988.

The previous prime is 206669987. The next prime is 206670007. The reversal of 206669989 is 989966602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 191130625 + 15539364 = 13825^2 + 3942^2 .

It is a cyclic number.

It is not a de Polignac number, because 206669989 - 2¹ = 206669987 is a prime.

Together with 206669987, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (206669987) 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, 103334994 + 103334995.

It is an arithmetic number, because the mean of its divisors is an integer number (103334995).

Almost surely, 2^206669989 is an apocalyptic number.

It is an amenable number.

206669989 is a deficient number, since it is larger than the sum of its proper divisors (1).

206669989 is an equidigital number, since it uses as much as digits as its factorization.

206669989 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2519424, while the sum is 55.

The square root of 206669989 is about 14376.0213202402. The cubic root of 206669989 is about 591.2336430179.

The spelling of 206669989 in words is "two hundred six million, six hundred sixty-nine thousand, nine hundred eighty-nine".