206423509 has 2 divisors, whose sum is σ = 206423510. Its totient is φ = 206423508.

The previous prime is 206423473. The next prime is 206423549. The reversal of 206423509 is 905324602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 111302500 + 95121009 = 10550^2 + 9753^2 .

It is a cyclic number.

It is not a de Polignac number, because 206423509 - 2¹¹ = 206421461 is a prime.

It is a super-2 number, since 2×206423509² = 85221330135746162, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (206423549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 103211754 + 103211755.

It is an arithmetic number, because the mean of its divisors is an integer number (103211755).

Almost surely, 2^206423509 is an apocalyptic number.

It is an amenable number.

206423509 is a deficient number, since it is larger than the sum of its proper divisors (1).

206423509 is an equidigital number, since it uses as much as digits as its factorization.

206423509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12960, while the sum is 31.

The square root of 206423509 is about 14367.4461544145. The cubic root of 206423509 is about 590.9985093149.

The spelling of 206423509 in words is "two hundred six million, four hundred twenty-three thousand, five hundred nine".