20711609 has 2 divisors, whose sum is σ = 20711610. Its totient is φ = 20711608.

The previous prime is 20711599. The next prime is 20711611. The reversal of 20711609 is 90611702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18318400 + 2393209 = 4280^2 + 1547^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20711609 is a prime.

Together with 20711611, 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 (20711629) 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, 10355804 + 10355805.

It is an arithmetic number, because the mean of its divisors is an integer number (10355805).

Almost surely, 2^20711609 is an apocalyptic number.

It is an amenable number.

20711609 is a deficient number, since it is larger than the sum of its proper divisors (1).

20711609 is an equidigital number, since it uses as much as digits as its factorization.

20711609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 756, while the sum is 26.

The square root of 20711609 is about 4551.0008789276. Note that the first 3 decimals coincide. The cubic root of 20711609 is about 274.6236571031.

The spelling of 20711609 in words is "twenty million, seven hundred eleven thousand, six hundred nine".