18861121 has 2 divisors, whose sum is σ = 18861122. Its totient is φ = 18861120.

The previous prime is 18861097. The next prime is 18861137. The reversal of 18861121 is 12116881.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13220496 + 5640625 = 3636^2 + 2375^2 .

It is a cyclic number.

It is not a de Polignac number, because 18861121 - 2⁹ = 18860609 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18861121.

It is not a weakly prime, because it can be changed into another prime (18861181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9430560 + 9430561.

It is an arithmetic number, because the mean of its divisors is an integer number (9430561).

Almost surely, 2^18861121 is an apocalyptic number.

It is an amenable number.

18861121 is a deficient number, since it is larger than the sum of its proper divisors (1).

18861121 is an equidigital number, since it uses as much as digits as its factorization.

18861121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 768, while the sum is 28.

The square root of 18861121 is about 4342.9392121005. The cubic root of 18861121 is about 266.1884252975.

The spelling of 18861121 in words is "eighteen million, eight hundred sixty-one thousand, one hundred twenty-one".