19681369 has 2 divisors, whose sum is σ = 19681370. Its totient is φ = 19681368.

The previous prime is 19681357. The next prime is 19681379. The reversal of 19681369 is 96318691.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19245769 + 435600 = 4387^2 + 660^2 .

It is a cyclic number.

It is not a de Polignac number, because 19681369 - 2⁷ = 19681241 is a prime.

It is a super-2 number, since 2×19681369² = 774712571428322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (19681339) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9840684 + 9840685.

It is an arithmetic number, because the mean of its divisors is an integer number (9840685).

Almost surely, 2^19681369 is an apocalyptic number.

It is an amenable number.

19681369 is a deficient number, since it is larger than the sum of its proper divisors (1).

19681369 is an equidigital number, since it uses as much as digits as its factorization.

19681369 is an evil number, because the sum of its binary digits is even.

The product of its digits is 69984, while the sum is 43.

The square root of 19681369 is about 4436.3688980967. The cubic root of 19681369 is about 269.9925420894.

The spelling of 19681369 in words is "nineteen million, six hundred eighty-one thousand, three hundred sixty-nine".