20168509 has 2 divisors, whose sum is σ = 20168510. Its totient is φ = 20168508.

The previous prime is 20168503. The next prime is 20168521. The reversal of 20168509 is 90586102.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20025625 + 142884 = 4475^2 + 378^2 .

It is a cyclic number.

It is not a de Polignac number, because 20168509 - 2⁷ = 20168381 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20168503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10084254 + 10084255.

It is an arithmetic number, because the mean of its divisors is an integer number (10084255).

Almost surely, 2^20168509 is an apocalyptic number.

It is an amenable number.

20168509 is a deficient number, since it is larger than the sum of its proper divisors (1).

20168509 is an equidigital number, since it uses as much as digits as its factorization.

20168509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4320, while the sum is 31.

The square root of 20168509 is about 4490.9363166271. The cubic root of 20168509 is about 272.2019702706.

The spelling of 20168509 in words is "twenty million, one hundred sixty-eight thousand, five hundred nine".