18891071 has 2 divisors, whose sum is σ = 18891072. Its totient is φ = 18891070.

The previous prime is 18891043. The next prime is 18891077. The reversal of 18891071 is 17019881.

It is a strong prime.

It is an emirp because it is prime and its reverse (17019881) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18891071 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18891077) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9445535 + 9445536.

It is an arithmetic number, because the mean of its divisors is an integer number (9445536).

Almost surely, 2^18891071 is an apocalyptic number.

18891071 is a deficient number, since it is larger than the sum of its proper divisors (1).

18891071 is an equidigital number, since it uses as much as digits as its factorization.

18891071 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4032, while the sum is 35.

The square root of 18891071 is about 4346.3859699755. The cubic root of 18891071 is about 266.3292463235.

The spelling of 18891071 in words is "eighteen million, eight hundred ninety-one thousand, seventy-one".