18891689 has 2 divisors, whose sum is σ = 18891690. Its totient is φ = 18891688.

The previous prime is 18891659. The next prime is 18891701. The reversal of 18891689 is 98619881.

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., 18344089 + 547600 = 4283^2 + 740^2 .

It is a cyclic number.

It is not a de Polignac number, because 18891689 - 2²⁰ = 17843113 is a prime.

It is not a weakly prime, because it can be changed into another prime (18891659) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9445844 + 9445845.

It is an arithmetic number, because the mean of its divisors is an integer number (9445845).

Almost surely, 2^18891689 is an apocalyptic number.

It is an amenable number.

18891689 is a deficient number, since it is larger than the sum of its proper divisors (1).

18891689 is an equidigital number, since it uses as much as digits as its factorization.

18891689 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 248832, while the sum is 50.

The square root of 18891689 is about 4346.4570629422. The cubic root of 18891689 is about 266.3321505118.

The spelling of 18891689 in words is "eighteen million, eight hundred ninety-one thousand, six hundred eighty-nine".