18665851 has 2 divisors, whose sum is σ = 18665852. Its totient is φ = 18665850.

The previous prime is 18665849. The next prime is 18665869. The reversal of 18665851 is 15856681.

It is a weak prime.

It is an emirp because it is prime and its reverse (15856681) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18665851 - 2¹ = 18665849 is a prime.

Together with 18665849, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18665891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9332925 + 9332926.

It is an arithmetic number, because the mean of its divisors is an integer number (9332926).

Almost surely, 2^18665851 is an apocalyptic number.

18665851 is a deficient number, since it is larger than the sum of its proper divisors (1).

18665851 is an equidigital number, since it uses as much as digits as its factorization.

18665851 is an evil number, because the sum of its binary digits is even.

The product of its digits is 57600, while the sum is 40.

The square root of 18665851 is about 4320.3994028330. The cubic root of 18665851 is about 265.2666166793.

The spelling of 18665851 in words is "eighteen million, six hundred sixty-five thousand, eight hundred fifty-one".