20648009 has 2 divisors, whose sum is σ = 20648010. Its totient is φ = 20648008.

The previous prime is 20647999. The next prime is 20648011. The reversal of 20648009 is 90084602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18088009 + 2560000 = 4253^2 + 1600^2 .

It is a cyclic number.

It is not a de Polignac number, because 20648009 - 2¹⁶ = 20582473 is a prime.

It is a Sophie Germain prime.

Together with 20648011, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (20648039) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10324004 + 10324005.

It is an arithmetic number, because the mean of its divisors is an integer number (10324005).

Almost surely, 2^20648009 is an apocalyptic number.

It is an amenable number.

20648009 is a deficient number, since it is larger than the sum of its proper divisors (1).

20648009 is an equidigital number, since it uses as much as digits as its factorization.

20648009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3456, while the sum is 29.

The square root of 20648009 is about 4544.0080325633. The cubic root of 20648009 is about 274.3422694511.

The spelling of 20648009 in words is "twenty million, six hundred forty-eight thousand, nine".