19998917 has 2 divisors, whose sum is σ = 19998918. Its totient is φ = 19998916.

The previous prime is 19998899. The next prime is 19998943. The reversal of 19998917 is 71989991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19838116 + 160801 = 4454^2 + 401^2 .

It is an emirp because it is prime and its reverse (71989991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19998917 - 2¹⁰ = 19997893 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 (19998977) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9999458 + 9999459.

It is an arithmetic number, because the mean of its divisors is an integer number (9999459).

Almost surely, 2^19998917 is an apocalyptic number.

It is an amenable number.

19998917 is a deficient number, since it is larger than the sum of its proper divisors (1).

19998917 is an equidigital number, since it uses as much as digits as its factorization.

19998917 is an evil number, because the sum of its binary digits is even.

The product of its digits is 367416, while the sum is 53.

The square root of 19998917 is about 4472.0148702794. The cubic root of 19998917 is about 271.4368620473.

The spelling of 19998917 in words is "nineteen million, nine hundred ninety-eight thousand, nine hundred seventeen".