19966897 has 2 divisors, whose sum is σ = 19966898. Its totient is φ = 19966896.

The previous prime is 19966873. The next prime is 19966901. The reversal of 19966897 is 79866991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19927296 + 39601 = 4464^2 + 199^2 .

It is an emirp because it is prime and its reverse (79866991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19966897 - 2⁷ = 19966769 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (19966847) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9983448 + 9983449.

It is an arithmetic number, because the mean of its divisors is an integer number (9983449).

Almost surely, 2^19966897 is an apocalyptic number.

It is an amenable number.

19966897 is a deficient number, since it is larger than the sum of its proper divisors (1).

19966897 is an equidigital number, since it uses as much as digits as its factorization.

19966897 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1469664, while the sum is 55.

The square root of 19966897 is about 4468.4333943788. The cubic root of 19966897 is about 271.2919200150.

The spelling of 19966897 in words is "nineteen million, nine hundred sixty-six thousand, eight hundred ninety-seven".