18891289 has 2 divisors, whose sum is σ = 18891290. Its totient is φ = 18891288.

The previous prime is 18891251. The next prime is 18891311. The reversal of 18891289 is 98219881.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12131289 + 6760000 = 3483^2 + 2600^2 .

It is a cyclic number.

It is not a de Polignac number, because 18891289 - 2¹⁹ = 18367001 is a prime.

It is not a weakly prime, because it can be changed into another prime (18891689) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9445644 + 9445645.

It is an arithmetic number, because the mean of its divisors is an integer number (9445645).

Almost surely, 2^18891289 is an apocalyptic number.

It is an amenable number.

18891289 is a deficient number, since it is larger than the sum of its proper divisors (1).

18891289 is an equidigital number, since it uses as much as digits as its factorization.

18891289 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 82944, while the sum is 46.

The square root of 18891289 is about 4346.4110482098. The cubic root of 18891289 is about 266.3302707855.

The spelling of 18891289 in words is "eighteen million, eight hundred ninety-one thousand, two hundred eighty-nine".