20768309 has 2 divisors, whose sum is σ = 20768310. Its totient is φ = 20768308.

The previous prime is 20768303. The next prime is 20768323. The reversal of 20768309 is 90386702.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13359025 + 7409284 = 3655^2 + 2722^2 .

It is a cyclic number.

It is not a de Polignac number, because 20768309 - 2¹² = 20764213 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20768303) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10384154 + 10384155.

It is an arithmetic number, because the mean of its divisors is an integer number (10384155).

Almost surely, 2^20768309 is an apocalyptic number.

It is an amenable number.

20768309 is a deficient number, since it is larger than the sum of its proper divisors (1).

20768309 is an equidigital number, since it uses as much as digits as its factorization.

20768309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18144, while the sum is 35.

The square root of 20768309 is about 4557.2260202891. The cubic root of 20768309 is about 274.8740315630.

The spelling of 20768309 in words is "twenty million, seven hundred sixty-eight thousand, three hundred nine".