18385421 has 2 divisors, whose sum is σ = 18385422. Its totient is φ = 18385420.

The previous prime is 18385417. The next prime is 18385429. The reversal of 18385421 is 12458381.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18369796 + 15625 = 4286^2 + 125^2 .

It is a cyclic number.

It is not a de Polignac number, because 18385421 - 2² = 18385417 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18385429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9192710 + 9192711.

It is an arithmetic number, because the mean of its divisors is an integer number (9192711).

Almost surely, 2^18385421 is an apocalyptic number.

It is an amenable number.

18385421 is a deficient number, since it is larger than the sum of its proper divisors (1).

18385421 is an equidigital number, since it uses as much as digits as its factorization.

18385421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7680, while the sum is 32.

The square root of 18385421 is about 4287.8224077030. The cubic root of 18385421 is about 263.9314799600.

The spelling of 18385421 in words is "eighteen million, three hundred eighty-five thousand, four hundred twenty-one".