18685421 has 4 divisors (see below), whose sum is σ = 18734592. Its totient is φ = 18636252.

The previous prime is 18685411. The next prime is 18685423. The reversal of 18685421 is 12458681.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 18685421 - 2⁶ = 18685357 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18685423) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24011 + ... + 24776.

It is an arithmetic number, because the mean of its divisors is an integer number (4683648).

Almost surely, 2^18685421 is an apocalyptic number.

It is an amenable number.

18685421 is a deficient number, since it is larger than the sum of its proper divisors (49171).

18685421 is an equidigital number, since it uses as much as digits as its factorization.

18685421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49170.

The product of its digits is 15360, while the sum is 35.

The square root of 18685421 is about 4322.6636464106. The cubic root of 18685421 is about 265.3592895592.

Adding to 18685421 its product of digits (15360), we get a palindrome (18700781).

The spelling of 18685421 in words is "eighteen million, six hundred eighty-five thousand, four hundred twenty-one".