19987169 has 2 divisors, whose sum is σ = 19987170. Its totient is φ = 19987168.

The previous prime is 19987159. The next prime is 19987171. The reversal of 19987169 is 96178991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18386944 + 1600225 = 4288^2 + 1265^2 .

It is an emirp because it is prime and its reverse (96178991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19987169 - 2⁴ = 19987153 is a prime.

It is a super-2 number, since 2×19987169² = 798973849269122, which contains 22 as substring.

Together with 19987171, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (19987109) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9993584 + 9993585.

It is an arithmetic number, because the mean of its divisors is an integer number (9993585).

Almost surely, 2^19987169 is an apocalyptic number.

It is an amenable number.

19987169 is a deficient number, since it is larger than the sum of its proper divisors (1).

19987169 is an equidigital number, since it uses as much as digits as its factorization.

19987169 is an odious number, because the sum of its binary digits is odd.

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

The square root of 19987169 is about 4470.7011754310. The cubic root of 19987169 is about 271.3837014208.

The spelling of 19987169 in words is "nineteen million, nine hundred eighty-seven thousand, one hundred sixty-nine".