16189981 has 2 divisors, whose sum is σ = 16189982. Its totient is φ = 16189980.

The previous prime is 16189969. The next prime is 16189991. The reversal of 16189981 is 18998161.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13912900 + 2277081 = 3730^2 + 1509^2 .

It is a cyclic number.

It is not a de Polignac number, because 16189981 - 2¹¹ = 16187933 is a prime.

It is a super-2 number, since 2×16189981² = 524230969560722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16189931) 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, 8094990 + 8094991.

It is an arithmetic number, because the mean of its divisors is an integer number (8094991).

Almost surely, 2^16189981 is an apocalyptic number.

It is an amenable number.

16189981 is a deficient number, since it is larger than the sum of its proper divisors (1).

16189981 is an equidigital number, since it uses as much as digits as its factorization.

16189981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 31104, while the sum is 43.

The square root of 16189981 is about 4023.6775467226. The cubic root of 16189981 is about 252.9776261675.

The spelling of 16189981 in words is "sixteen million, one hundred eighty-nine thousand, nine hundred eighty-one".