19717889 has 2 divisors, whose sum is σ = 19717890. Its totient is φ = 19717888.

The previous prime is 19717879. The next prime is 19717903. The reversal of 19717889 is 98871791.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18318400 + 1399489 = 4280^2 + 1183^2 .

It is a cyclic number.

It is not a de Polignac number, because 19717889 - 2²⁴ = 2940673 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (19717849) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9858944 + 9858945.

It is an arithmetic number, because the mean of its divisors is an integer number (9858945).

Almost surely, 2^19717889 is an apocalyptic number.

It is an amenable number.

19717889 is a deficient number, since it is larger than the sum of its proper divisors (1).

19717889 is an equidigital number, since it uses as much as digits as its factorization.

19717889 is an evil number, because the sum of its binary digits is even.

The product of its digits is 254016, while the sum is 50.

The square root of 19717889 is about 4440.4829692276. The cubic root of 19717889 is about 270.1594348705.

The spelling of 19717889 in words is "nineteen million, seven hundred seventeen thousand, eight hundred eighty-nine".