20840489 has 2 divisors, whose sum is σ = 20840490. Its totient is φ = 20840488.

The previous prime is 20840471. The next prime is 20840503. The reversal of 20840489 is 98404802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18344089 + 2496400 = 4283^2 + 1580^2 .

It is a cyclic number.

It is not a de Polignac number, because 20840489 - 2⁸ = 20840233 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (20840429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10420244 + 10420245.

It is an arithmetic number, because the mean of its divisors is an integer number (10420245).

Almost surely, 2^20840489 is an apocalyptic number.

It is an amenable number.

20840489 is a deficient number, since it is larger than the sum of its proper divisors (1).

20840489 is an equidigital number, since it uses as much as digits as its factorization.

20840489 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 18432, while the sum is 35.

The square root of 20840489 is about 4565.1384425886. The cubic root of 20840489 is about 275.1921037894.

The spelling of 20840489 in words is "twenty million, eight hundred forty thousand, four hundred eighty-nine".