20666197 has 2 divisors, whose sum is σ = 20666198. Its totient is φ = 20666196.

The previous prime is 20666179. The next prime is 20666201. The reversal of 20666197 is 79166602.

Together with previous prime (20666179) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20666116 + 81 = 4546^2 + 9^2 .

It is a cyclic number.

It is not a de Polignac number, because 20666197 - 2¹⁵ = 20633429 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 (20666147) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10333098 + 10333099.

It is an arithmetic number, because the mean of its divisors is an integer number (10333099).

Almost surely, 2^20666197 is an apocalyptic number.

It is an amenable number.

20666197 is a deficient number, since it is larger than the sum of its proper divisors (1).

20666197 is an equidigital number, since it uses as much as digits as its factorization.

20666197 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 27216, while the sum is 37.

The square root of 20666197 is about 4546.0089089222. The cubic root of 20666197 is about 274.4227981650.

The spelling of 20666197 in words is "twenty million, six hundred sixty-six thousand, one hundred ninety-seven".