20849009 has 2 divisors, whose sum is σ = 20849010. Its totient is φ = 20849008.

The previous prime is 20848991. The next prime is 20849011. The reversal of 20849009 is 90094802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20430400 + 418609 = 4520^2 + 647^2 .

It is a cyclic number.

It is not a de Polignac number, because 20849009 - 2⁸ = 20848753 is a prime.

Together with 20849011, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20849029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10424504 + 10424505.

It is an arithmetic number, because the mean of its divisors is an integer number (10424505).

Almost surely, 2^20849009 is an apocalyptic number.

It is an amenable number.

20849009 is a deficient number, since it is larger than the sum of its proper divisors (1).

20849009 is an equidigital number, since it uses as much as digits as its factorization.

20849009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5184, while the sum is 32.

The square root of 20849009 is about 4566.0715062294. The cubic root of 20849009 is about 275.2295999871.

The spelling of 20849009 in words is "twenty million, eight hundred forty-nine thousand, nine".