20909789 has 2 divisors, whose sum is σ = 20909790. Its totient is φ = 20909788.

The previous prime is 20909771. The next prime is 20909821. The reversal of 20909789 is 98790902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16949689 + 3960100 = 4117^2 + 1990^2 .

It is a cyclic number.

It is not a de Polignac number, because 20909789 - 2⁸ = 20909533 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 (20909089) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10454894 + 10454895.

It is an arithmetic number, because the mean of its divisors is an integer number (10454895).

Almost surely, 2^20909789 is an apocalyptic number.

It is an amenable number.

20909789 is a deficient number, since it is larger than the sum of its proper divisors (1).

20909789 is an equidigital number, since it uses as much as digits as its factorization.

20909789 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 81648, while the sum is 44.

The square root of 20909789 is about 4572.7222745319. The cubic root of 20909789 is about 275.4967945495.

The spelling of 20909789 in words is "twenty million, nine hundred nine thousand, seven hundred eighty-nine".