18187121 has 2 divisors, whose sum is σ = 18187122. Its totient is φ = 18187120.

The previous prime is 18187063. The next prime is 18187133. The reversal of 18187121 is 12178181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10144225 + 8042896 = 3185^2 + 2836^2 .

It is a cyclic number.

It is not a de Polignac number, because 18187121 - 2²² = 13992817 is a prime.

It is not a weakly prime, because it can be changed into another prime (18186121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9093560 + 9093561.

It is an arithmetic number, because the mean of its divisors is an integer number (9093561).

Almost surely, 2^18187121 is an apocalyptic number.

It is an amenable number.

18187121 is a deficient number, since it is larger than the sum of its proper divisors (1).

18187121 is an equidigital number, since it uses as much as digits as its factorization.

18187121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 896, while the sum is 29.

The square root of 18187121 is about 4264.6360923296. The cubic root of 18187121 is about 262.9791508578.

The spelling of 18187121 in words is "eighteen million, one hundred eighty-seven thousand, one hundred twenty-one".