18045781 has 8 divisors (see below), whose sum is σ = 19908504. Its totient is φ = 16250880.

The previous prime is 18045773. The next prime is 18045787. The reversal of 18045781 is 18754081.

It can be written as a sum of positive squares in 4 ways, for example, as 1602756 + 16443025 = 1266^2 + 4055^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 18045781 - 2³ = 18045773 is a prime.

It is a super-2 number, since 2×18045781² = 651300423799922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18045787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16396 + ... + 17461.

It is an arithmetic number, because the mean of its divisors is an integer number (2488563).

Almost surely, 2^18045781 is an apocalyptic number.

It is an amenable number.

18045781 is a deficient number, since it is larger than the sum of its proper divisors (1862723).

18045781 is a wasteful number, since it uses less digits than its factorization.

18045781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33911.

The product of its (nonzero) digits is 8960, while the sum is 34.

The square root of 18045781 is about 4248.0326034530. The cubic root of 18045781 is about 262.2961368033.

The spelling of 18045781 in words is "eighteen million, forty-five thousand, seven hundred eighty-one".