19998617 has 2 divisors, whose sum is σ = 19998618. Its totient is φ = 19998616.

The previous prime is 19998607. The next prime is 19998637. The reversal of 19998617 is 71689991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19456921 + 541696 = 4411^2 + 736^2 .

It is an emirp because it is prime and its reverse (71689991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19998617 - 2⁶ = 19998553 is a prime.

It is a super-3 number, since 3×19998617³ (a number of 23 digits) contains 333 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (19998607) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9999308 + 9999309.

It is an arithmetic number, because the mean of its divisors is an integer number (9999309).

Almost surely, 2^19998617 is an apocalyptic number.

It is an amenable number.

19998617 is a deficient number, since it is larger than the sum of its proper divisors (1).

19998617 is an equidigital number, since it uses as much as digits as its factorization.

19998617 is an evil number, because the sum of its binary digits is even.

The product of its digits is 244944, while the sum is 50.

The square root of 19998617 is about 4471.9813282258. The cubic root of 19998617 is about 271.4355047827.

The spelling of 19998617 in words is "nineteen million, nine hundred ninety-eight thousand, six hundred seventeen".