18000081 has 18 divisors (see below), whose sum is σ = 28580370. Its totient is φ = 10908480.

The previous prime is 18000067. The next prime is 18000089.

It is a happy number.

18000081 is nontrivially palindromic in base 10.

It can be written as a sum of positive squares in only one way, i.e., 17564481 + 435600 = 4191^2 + 660^2 .

It is not a de Polignac number, because 18000081 - 2⁷ = 17999953 is a prime.

It is a super-2 number, since 2×18000081² = 648005832013122, which contains 22 as substring.

18000081 is a strobogrammatic number because it is the same when read upside-down.

18000081 is a modest number, since divided by 81 gives 18 as remainder.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18000089) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 7176 + ... + 9353.

Almost surely, 2^18000081 is an apocalyptic number.

18000081 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18000081 is a deficient number, since it is larger than the sum of its proper divisors (10580289).

18000081 is a wasteful number, since it uses less digits than its factorization.

18000081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16557 (or 16543 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 18.

The square root of 18000081 is about 4242.6502330501. The cubic root of 18000081 is about 262.0745325315.

It can be divided in two parts, 180000 and 81, that added together give a palindrome (180081).

The spelling of 18000081 in words is "eighteen million, eighty-one", and thus it is an aban number and an uban number.