18120813 has 16 divisors (see below), whose sum is σ = 25552320. Its totient is φ = 11390976.

The previous prime is 18120799. The next prime is 18120829. The reversal of 18120813 is 31802181.

It is not a de Polignac number, because 18120813 - 2⁴ = 18120797 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18120013) 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, 14031 + ... + 15267.

It is an arithmetic number, because the mean of its divisors is an integer number (1597020).

Almost surely, 2^18120813 is an apocalyptic number.

It is an amenable number.

18120813 is a deficient number, since it is larger than the sum of its proper divisors (7431507).

18120813 is a wasteful number, since it uses less digits than its factorization.

18120813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1516.

The product of its (nonzero) digits is 384, while the sum is 24.

The square root of 18120813 is about 4256.8548248678. The cubic root of 18120813 is about 262.6591651498.

Adding to 18120813 its reverse (31802181), we get a palindrome (49922994).

The spelling of 18120813 in words is "eighteen million, one hundred twenty thousand, eight hundred thirteen".