20826209 has 2 divisors, whose sum is σ = 20826210. Its totient is φ = 20826208.

The previous prime is 20826199. The next prime is 20826251. The reversal of 20826209 is 90262802.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18515809 + 2310400 = 4303^2 + 1520^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20826209 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 (20826409) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10413104 + 10413105.

It is an arithmetic number, because the mean of its divisors is an integer number (10413105).

Almost surely, 2^20826209 is an apocalyptic number.

It is an amenable number.

20826209 is a deficient number, since it is larger than the sum of its proper divisors (1).

20826209 is an equidigital number, since it uses as much as digits as its factorization.

20826209 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 20826209 is about 4563.5741475295. The cubic root of 20826209 is about 275.1292351247.

The spelling of 20826209 in words is "twenty million, eight hundred twenty-six thousand, two hundred nine".