20018909 has 2 divisors, whose sum is σ = 20018910. Its totient is φ = 20018908.

The previous prime is 20018893. The next prime is 20018923. The reversal of 20018909 is 90981002.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10272025 + 9746884 = 3205^2 + 3122^2 .

It is a cyclic number.

It is not a de Polignac number, because 20018909 - 2⁴ = 20018893 is a prime.

It is a super-3 number, since 3×20018909³ (a number of 23 digits) contains 333 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20018959) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10009454 + 10009455.

It is an arithmetic number, because the mean of its divisors is an integer number (10009455).

Almost surely, 2^20018909 is an apocalyptic number.

It is an amenable number.

20018909 is a deficient number, since it is larger than the sum of its proper divisors (1).

20018909 is an equidigital number, since it uses as much as digits as its factorization.

20018909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1296, while the sum is 29.

The square root of 20018909 is about 4474.2495460133. The cubic root of 20018909 is about 271.5272795854.

The spelling of 20018909 in words is "twenty million, eighteen thousand, nine hundred nine".