20912789 has 2 divisors, whose sum is σ = 20912790. Its totient is φ = 20912788.

The previous prime is 20912783. The next prime is 20912803. The reversal of 20912789 is 98721902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20884900 + 27889 = 4570^2 + 167^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20912789 is a prime.

It is a Sophie Germain prime.

It is a Chen 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 (20912783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10456394 + 10456395.

It is an arithmetic number, because the mean of its divisors is an integer number (10456395).

Almost surely, 2^20912789 is an apocalyptic number.

It is an amenable number.

20912789 is a deficient number, since it is larger than the sum of its proper divisors (1).

20912789 is an equidigital number, since it uses as much as digits as its factorization.

20912789 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 38.

The square root of 20912789 is about 4573.0502949344. The cubic root of 20912789 is about 275.5099694132.

The spelling of 20912789 in words is "twenty million, nine hundred twelve thousand, seven hundred eighty-nine".