18551971 has 2 divisors, whose sum is σ = 18551972. Its totient is φ = 18551970.

The previous prime is 18551969. The next prime is 18551989. The reversal of 18551971 is 17915581.

It is a weak prime.

It is an emirp because it is prime and its reverse (17915581) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18551971 - 2¹ = 18551969 is a prime.

Together with 18551969, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 18551971.

It is not a weakly prime, because it can be changed into another prime (18551921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9275985 + 9275986.

It is an arithmetic number, because the mean of its divisors is an integer number (9275986).

Almost surely, 2^18551971 is an apocalyptic number.

18551971 is a deficient number, since it is larger than the sum of its proper divisors (1).

18551971 is an equidigital number, since it uses as much as digits as its factorization.

18551971 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12600, while the sum is 37.

The square root of 18551971 is about 4307.1999024889. The cubic root of 18551971 is about 264.7260536776.

The spelling of 18551971 in words is "eighteen million, five hundred fifty-one thousand, nine hundred seventy-one".