18181705 has 4 divisors (see below), whose sum is σ = 21818052. Its totient is φ = 14545360.

The previous prime is 18181679. The next prime is 18181729. The reversal of 18181705 is 50718181.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50718181 = 139 ⋅364879.

It can be written as a sum of positive squares in 2 ways, for example, as 6533136 + 11648569 = 2556^2 + 3413^2 .

It is not a de Polignac number, because 18181705 - 2⁷ = 18181577 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1818166 + ... + 1818175.

It is an arithmetic number, because the mean of its divisors is an integer number (5454513).

Almost surely, 2^18181705 is an apocalyptic number.

It is an amenable number.

18181705 is a deficient number, since it is larger than the sum of its proper divisors (3636347).

18181705 is an equidigital number, since it uses as much as digits as its factorization.

18181705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3636346.

The product of its (nonzero) digits is 2240, while the sum is 31.

The square root of 18181705 is about 4264.0010553470. The cubic root of 18181705 is about 262.9530438031.

Adding to 18181705 its reverse (50718181), we get a palindrome (68899886).

The spelling of 18181705 in words is "eighteen million, one hundred eighty-one thousand, seven hundred five".