18042981 has 16 divisors (see below), whose sum is σ = 26334720. Its totient is φ = 10897520.

The previous prime is 18042979. The next prime is 18043009. The reversal of 18042981 is 18924081.

It is a cyclic number.

It is not a de Polignac number, because 18042981 - 2¹ = 18042979 is a prime.

It is a super-2 number, since 2×18042981² = 651098326732722, which contains 22 as substring.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18042181) 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, 11086 + ... + 12608.

It is an arithmetic number, because the mean of its divisors is an integer number (1645920).

Almost surely, 2^18042981 is an apocalyptic number.

18042981 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18042981 is a deficient number, since it is larger than the sum of its proper divisors (8291739).

18042981 is a wasteful number, since it uses less digits than its factorization.

18042981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1896.

The product of its (nonzero) digits is 4608, while the sum is 33.

The square root of 18042981 is about 4247.7030263426. The cubic root of 18042981 is about 262.2825700649.

The spelling of 18042981 in words is "eighteen million, forty-two thousand, nine hundred eighty-one".