18891473 has 2 divisors, whose sum is σ = 18891474. Its totient is φ = 18891472.

The previous prime is 18891469. The next prime is 18891527. The reversal of 18891473 is 37419881.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16224784 + 2666689 = 4028^2 + 1633^2 .

It is a cyclic number.

It is not a de Polignac number, because 18891473 - 2² = 18891469 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 18891473.

It is not a weakly prime, because it can be changed into another prime (18891443) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9445736 + 9445737.

It is an arithmetic number, because the mean of its divisors is an integer number (9445737).

Almost surely, 2^18891473 is an apocalyptic number.

It is an amenable number.

18891473 is a deficient number, since it is larger than the sum of its proper divisors (1).

18891473 is an equidigital number, since it uses as much as digits as its factorization.

18891473 is an evil number, because the sum of its binary digits is even.

The product of its digits is 48384, while the sum is 41.

The square root of 18891473 is about 4346.4322150472. The cubic root of 18891473 is about 266.3311354629.

The spelling of 18891473 in words is "eighteen million, eight hundred ninety-one thousand, four hundred seventy-three".