20818145 has 4 divisors (see below), whose sum is σ = 24981780. Its totient is φ = 16654512.

The previous prime is 20818139. The next prime is 20818153. The reversal of 20818145 is 54181802.

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

It can be written as a sum of positive squares in 2 ways, for example, as 6431296 + 14386849 = 2536^2 + 3793^2 .

It is a cyclic number.

It is not a de Polignac number, because 20818145 - 2⁸ = 20817889 is a prime.

It is a super-2 number, since 2×20818145² = 866790322482050, which contains 22 as substring.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 2081810 + ... + 2081819.

It is an arithmetic number, because the mean of its divisors is an integer number (6245445).

Almost surely, 2^20818145 is an apocalyptic number.

It is an amenable number.

20818145 is a deficient number, since it is larger than the sum of its proper divisors (4163635).

20818145 is an equidigital number, since it uses as much as digits as its factorization.

20818145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4163634.

The product of its (nonzero) digits is 2560, while the sum is 29.

The square root of 20818145 is about 4562.6905439664. The cubic root of 20818145 is about 275.0937201226.

Adding to 20818145 its reverse (54181802), we get a palindrome (74999947).

The spelling of 20818145 in words is "twenty million, eight hundred eighteen thousand, one hundred forty-five".