18020421 has 8 divisors (see below), whose sum is σ = 26696960. Its totient is φ = 12013596.

The previous prime is 18020413. The next prime is 18020441. The reversal of 18020421 is 12402081.

It is not a de Polignac number, because 18020421 - 2³ = 18020413 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18020394 and 18020403.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18020441) 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 in 7 ways as a sum of consecutive naturals, for example, 333685 + ... + 333738.

It is an arithmetic number, because the mean of its divisors is an integer number (3337120).

Almost surely, 2^18020421 is an apocalyptic number.

It is an amenable number.

18020421 is a deficient number, since it is larger than the sum of its proper divisors (8676539).

18020421 is an equidigital number, since it uses as much as digits as its factorization.

18020421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 667432 (or 667426 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

The square root of 18020421 is about 4245.0466428533. The cubic root of 18020421 is about 262.1732096690.

The spelling of 18020421 in words is "eighteen million, twenty thousand, four hundred twenty-one".