18821111 has 2 divisors, whose sum is σ = 18821112. Its totient is φ = 18821110.

The previous prime is 18821083. The next prime is 18821119. The reversal of 18821111 is 11112881.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18821111 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18821119) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9410555 + 9410556.

It is an arithmetic number, because the mean of its divisors is an integer number (9410556).

Almost surely, 2^18821111 is an apocalyptic number.

18821111 is a deficient number, since it is larger than the sum of its proper divisors (1).

18821111 is an equidigital number, since it uses as much as digits as its factorization.

18821111 is an evil number, because the sum of its binary digits is even.

The product of its digits is 128, while the sum is 23.

The square root of 18821111 is about 4338.3304392358. The cubic root of 18821111 is about 266.0000706654. Note that the first 4 decimals are identical.

Adding to 18821111 its reverse (11112881), we get a palindrome (29933992).

It can be divided in two parts, 1882 and 1111, that multiplied together give a palindrome (2090902).

The spelling of 18821111 in words is "eighteen million, eight hundred twenty-one thousand, one hundred eleven".