19009981 has 2 divisors, whose sum is σ = 19009982. Its totient is φ = 19009980.

The previous prime is 19009973. The next prime is 19010009. The reversal of 19009981 is 18990091.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12425625 + 6584356 = 3525^2 + 2566^2 .

It is an emirp because it is prime and its reverse (18990091) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19009981 - 2³ = 19009973 is a prime.

It is a super-2 number, since 2×19009981² = 722758755240722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 19009981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19009901) 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, 9504990 + 9504991.

It is an arithmetic number, because the mean of its divisors is an integer number (9504991).

Almost surely, 2^19009981 is an apocalyptic number.

It is an amenable number.

19009981 is a deficient number, since it is larger than the sum of its proper divisors (1).

19009981 is an equidigital number, since it uses as much as digits as its factorization.

19009981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5832, while the sum is 37.

The square root of 19009981 is about 4360.0436924416. The cubic root of 19009981 is about 266.8868818101.

It can be divided in two parts, 1900 and 9981, that added together give a square (11881 = 109²).

The spelling of 19009981 in words is "nineteen million, nine thousand, nine hundred eighty-one".