20665859 has 2 divisors, whose sum is σ = 20665860. Its totient is φ = 20665858.

The previous prime is 20665849. The next prime is 20665867. The reversal of 20665859 is 95856602.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20665859 - 2¹² = 20661763 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20665819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10332929 + 10332930.

It is an arithmetic number, because the mean of its divisors is an integer number (10332930).

Almost surely, 2^20665859 is an apocalyptic number.

20665859 is a deficient number, since it is larger than the sum of its proper divisors (1).

20665859 is an equidigital number, since it uses as much as digits as its factorization.

20665859 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 129600, while the sum is 41.

The square root of 20665859 is about 4545.9717333041. The cubic root of 20665859 is about 274.4213020760.

The spelling of 20665859 in words is "twenty million, six hundred sixty-five thousand, eight hundred fifty-nine".