19989917 has 2 divisors, whose sum is σ = 19989918. Its totient is φ = 19989916.

The previous prime is 19989911. The next prime is 19989971. The reversal of 19989917 is 71998991.

Together with next prime (19989971) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19971961 + 17956 = 4469^2 + 134^2 .

It is a cyclic number.

It is not a de Polignac number, because 19989917 - 2¹² = 19985821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19989911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9994958 + 9994959.

It is an arithmetic number, because the mean of its divisors is an integer number (9994959).

Almost surely, 2^19989917 is an apocalyptic number.

It is an amenable number.

19989917 is a deficient number, since it is larger than the sum of its proper divisors (1).

19989917 is an equidigital number, since it uses as much as digits as its factorization.

19989917 is an odious number, because the sum of its binary digits is odd.

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

The square root of 19989917 is about 4471.0084992091. The cubic root of 19989917 is about 271.3961382036.

The spelling of 19989917 in words is "nineteen million, nine hundred eighty-nine thousand, nine hundred seventeen".