20905559 has 2 divisors, whose sum is σ = 20905560. Its totient is φ = 20905558.

The previous prime is 20905519. The next prime is 20905579. The reversal of 20905559 is 95550902.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20905559 - 2⁸ = 20905303 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20905519) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10452779 + 10452780.

It is an arithmetic number, because the mean of its divisors is an integer number (10452780).

Almost surely, 2^20905559 is an apocalyptic number.

20905559 is a deficient number, since it is larger than the sum of its proper divisors (1).

20905559 is an equidigital number, since it uses as much as digits as its factorization.

20905559 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20250, while the sum is 35.

The square root of 20905559 is about 4572.2597257811. The cubic root of 20905559 is about 275.4782158504.

The spelling of 20905559 in words is "twenty million, nine hundred five thousand, five hundred fifty-nine".