18115261 has 2 divisors, whose sum is σ = 18115262. Its totient is φ = 18115260.

The previous prime is 18115243. The next prime is 18115277. The reversal of 18115261 is 16251181.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17589636 + 525625 = 4194^2 + 725^2 .

It is a cyclic number.

It is not a de Polignac number, because 18115261 - 2⁷ = 18115133 is a prime.

It is equal to p_1158190 and since 18115261 and 1158190 have the same sum of digits, it is a Honaker prime.

It is a plaindrome in base 16.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18115211) by changing a digit.

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 as a sum of consecutive naturals, namely, 9057630 + 9057631.

It is an arithmetic number, because the mean of its divisors is an integer number (9057631).

Almost surely, 2^18115261 is an apocalyptic number.

It is an amenable number.

18115261 is a deficient number, since it is larger than the sum of its proper divisors (1).

18115261 is an equidigital number, since it uses as much as digits as its factorization.

18115261 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 480, while the sum is 25.

The square root of 18115261 is about 4256.2026502506. The cubic root of 18115261 is about 262.6323372025.

The spelling of 18115261 in words is "eighteen million, one hundred fifteen thousand, two hundred sixty-one".