20945609 has 2 divisors, whose sum is σ = 20945610. Its totient is φ = 20945608.

The previous prime is 20945591. The next prime is 20945621. The reversal of 20945609 is 90654902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20675209 + 270400 = 4547^2 + 520^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20945609 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20945209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10472804 + 10472805.

It is an arithmetic number, because the mean of its divisors is an integer number (10472805).

Almost surely, 2^20945609 is an apocalyptic number.

It is an amenable number.

20945609 is a deficient number, since it is larger than the sum of its proper divisors (1).

20945609 is an equidigital number, since it uses as much as digits as its factorization.

20945609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 19440, while the sum is 35.

The square root of 20945609 is about 4576.6373026492. The cubic root of 20945609 is about 275.6540201995.

The spelling of 20945609 in words is "twenty million, nine hundred forty-five thousand, six hundred nine".