18120811 has 4 divisors (see below), whose sum is σ = 18562824. Its totient is φ = 17678800.

The previous prime is 18120799. The next prime is 18120829. The reversal of 18120811 is 11802181.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 18120811 - 2⁵ = 18120779 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18120871) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 220945 + ... + 221026.

It is an arithmetic number, because the mean of its divisors is an integer number (4640706).

Almost surely, 2^18120811 is an apocalyptic number.

18120811 is a deficient number, since it is larger than the sum of its proper divisors (442013).

18120811 is an equidigital number, since it uses as much as digits as its factorization.

18120811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 442012.

The product of its (nonzero) digits is 128, while the sum is 22.

The square root of 18120811 is about 4256.8545899525. The cubic root of 18120811 is about 262.6591554865.

Adding to 18120811 its reverse (11802181), we get a palindrome (29922992).

The spelling of 18120811 in words is "eighteen million, one hundred twenty thousand, eight hundred eleven".