20611909 has 2 divisors, whose sum is σ = 20611910. Its totient is φ = 20611908.

The previous prime is 20611907. The next prime is 20611919. The reversal of 20611909 is 90911602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19936225 + 675684 = 4465^2 + 822^2 .

It is a cyclic number.

It is not a de Polignac number, because 20611909 - 2¹ = 20611907 is a prime.

Together with 20611907, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20611901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10305954 + 10305955.

It is an arithmetic number, because the mean of its divisors is an integer number (10305955).

Almost surely, 2^20611909 is an apocalyptic number.

It is an amenable number.

20611909 is a deficient number, since it is larger than the sum of its proper divisors (1).

20611909 is an equidigital number, since it uses as much as digits as its factorization.

20611909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 972, while the sum is 28.

The square root of 20611909 is about 4540.0340307095. The cubic root of 20611909 is about 274.1822938446.

The spelling of 20611909 in words is "twenty million, six hundred eleven thousand, nine hundred nine".