19866481 has 2 divisors, whose sum is σ = 19866482. Its totient is φ = 19866480.

The previous prime is 19866463. The next prime is 19866527. The reversal of 19866481 is 18466891.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19713600 + 152881 = 4440^2 + 391^2 .

It is an emirp because it is prime and its reverse (18466891) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19866481 - 2²¹ = 17769329 is a prime.

It is a super-3 number, since 3×19866481³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not a weakly prime, because it can be changed into another prime (19860481) 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, 9933240 + 9933241.

It is an arithmetic number, because the mean of its divisors is an integer number (9933241).

Almost surely, 2^19866481 is an apocalyptic number.

It is an amenable number.

19866481 is a deficient number, since it is larger than the sum of its proper divisors (1).

19866481 is an equidigital number, since it uses as much as digits as its factorization.

19866481 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 82944, while the sum is 43.

The square root of 19866481 is about 4457.1830790310. The cubic root of 19866481 is about 270.8363685866.

The spelling of 19866481 in words is "nineteen million, eight hundred sixty-six thousand, four hundred eighty-one".