17998981 has 16 divisors (see below), whose sum is σ = 24167808. Its totient is φ = 12945600.

The previous prime is 17998973. The next prime is 17998993. The reversal of 17998981 is 18989971.

It is a cyclic number.

It is not a de Polignac number, because 17998981 - 2³ = 17998973 is a prime.

It is a super-2 number, since 2×17998981² = 647926634076722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (17998901) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7990 + ... + 9991.

It is an arithmetic number, because the mean of its divisors is an integer number (1510488).

Almost surely, 2^17998981 is an apocalyptic number.

17998981 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

17998981 is a deficient number, since it is larger than the sum of its proper divisors (6168827).

17998981 is a wasteful number, since it uses less digits than its factorization.

17998981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18012.

The product of its digits is 326592, while the sum is 52.

The square root of 17998981 is about 4242.5205951180. The cubic root of 17998981 is about 262.0691938915.

The spelling of 17998981 in words is "seventeen million, nine hundred ninety-eight thousand, nine hundred eighty-one".