18122561 has 12 divisors (see below), whose sum is σ = 20258532. Its totient is φ = 16153344.

The previous prime is 18122557. The next prime is 18122591. The reversal of 18122561 is 16522181.

It can be written as a sum of positive squares in 2 ways, for example, as 14440000 + 3682561 = 3800^2 + 1919^2 .

It is not a de Polignac number, because 18122561 - 2² = 18122557 is a prime.

It is a super-3 number, since 3×18122561³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 18122561.

It is not an unprimeable number, because it can be changed into a prime (18122501) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4661 + ... + 7613.

It is an arithmetic number, because the mean of its divisors is an integer number (1688211).

Almost surely, 2^18122561 is an apocalyptic number.

It is an amenable number.

18122561 is a deficient number, since it is larger than the sum of its proper divisors (2135971).

18122561 is a wasteful number, since it uses less digits than its factorization.

18122561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3008 (or 2989 counting only the distinct ones).

The product of its digits is 960, while the sum is 26.

The square root of 18122561 is about 4257.0601358214. The cubic root of 18122561 is about 262.6676105666.

The spelling of 18122561 in words is "eighteen million, one hundred twenty-two thousand, five hundred sixty-one".