18017981 has 2 divisors, whose sum is σ = 18017982. Its totient is φ = 18017980.

The previous prime is 18017959. The next prime is 18018017. The reversal of 18017981 is 18971081.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9665881 + 8352100 = 3109^2 + 2890^2 .

It is a cyclic number.

It is not a de Polignac number, because 18017981 - 2⁶ = 18017917 is a prime.

It is a super-2 number, since 2×18017981² = 649295278632722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18017911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9008990 + 9008991.

It is an arithmetic number, because the mean of its divisors is an integer number (9008991).

Almost surely, 2^18017981 is an apocalyptic number.

It is an amenable number.

18017981 is a deficient number, since it is larger than the sum of its proper divisors (1).

18017981 is an equidigital number, since it uses as much as digits as its factorization.

18017981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4032, while the sum is 35.

The square root of 18017981 is about 4244.7592393444. The cubic root of 18017981 is about 262.1613762143.

The spelling of 18017981 in words is "eighteen million, seventeen thousand, nine hundred eighty-one".