18981871 has 2 divisors, whose sum is σ = 18981872. Its totient is φ = 18981870.

The previous prime is 18981847. The next prime is 18981881. The reversal of 18981871 is 17818981.

It is a strong prime.

It is an emirp because it is prime and its reverse (17818981) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18981871 - 2⁹ = 18981359 is a prime.

It is a super-2 number, since 2×18981871² = 720622853321282, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18981821) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9490935 + 9490936.

It is an arithmetic number, because the mean of its divisors is an integer number (9490936).

Almost surely, 2^18981871 is an apocalyptic number.

18981871 is a deficient number, since it is larger than the sum of its proper divisors (1).

18981871 is an equidigital number, since it uses as much as digits as its factorization.

18981871 is an evil number, because the sum of its binary digits is even.

The product of its digits is 32256, while the sum is 43.

The square root of 18981871 is about 4356.8189083321. The cubic root of 18981871 is about 266.7552686484.

The spelling of 18981871 in words is "eighteen million, nine hundred eighty-one thousand, eight hundred seventy-one".