21605611 has 2 divisors, whose sum is σ = 21605612. Its totient is φ = 21605610.

The previous prime is 21605593. The next prime is 21605627. The reversal of 21605611 is 11650612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21605611 - 2⁹ = 21605099 is a prime.

It is a Chen prime.

It is a zygodrome in base 3.

It is not a weakly prime, because it can be changed into another prime (21605411) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10802805 + 10802806.

It is an arithmetic number, because the mean of its divisors is an integer number (10802806).

Almost surely, 2^21605611 is an apocalyptic number.

21605611 is a deficient number, since it is larger than the sum of its proper divisors (1).

21605611 is an equidigital number, since it uses as much as digits as its factorization.

21605611 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 21605611 is about 4648.1836237395. The cubic root of 21605611 is about 278.5194427021.

The spelling of 21605611 in words is "twenty-one million, six hundred five thousand, six hundred eleven".