18809971 has 2 divisors, whose sum is σ = 18809972. Its totient is φ = 18809970.

The previous prime is 18809969. The next prime is 18809977. The reversal of 18809971 is 17990881.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18809971 - 2¹ = 18809969 is a prime.

Together with 18809969, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (18809977) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9404985 + 9404986.

It is an arithmetic number, because the mean of its divisors is an integer number (9404986).

Almost surely, 2^18809971 is an apocalyptic number.

18809971 is a deficient number, since it is larger than the sum of its proper divisors (1).

18809971 is an equidigital number, since it uses as much as digits as its factorization.

18809971 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36288, while the sum is 43.

The square root of 18809971 is about 4337.0463451524. The cubic root of 18809971 is about 265.9475795095.

The spelling of 18809971 in words is "eighteen million, eight hundred nine thousand, nine hundred seventy-one".