18810421 has 16 divisors (see below), whose sum is σ = 22036608. Its totient is φ = 15724800.

The previous prime is 18810419. The next prime is 18810427. The reversal of 18810421 is 12401881.

It is not a de Polignac number, because 18810421 - 2¹ = 18810419 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 (18810427) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 66801 + ... + 67081.

It is an arithmetic number, because the mean of its divisors is an integer number (1377288).

Almost surely, 2^18810421 is an apocalyptic number.

It is an amenable number.

18810421 is a deficient number, since it is larger than the sum of its proper divisors (3226187).

18810421 is a wasteful number, since it uses less digits than its factorization.

18810421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 492.

The product of its (nonzero) digits is 512, while the sum is 25.

The square root of 18810421 is about 4337.0982234669. The cubic root of 18810421 is about 265.9497002899.

It can be divided in two parts, 188 and 10421, that added together give a square (10609 = 103²).

The spelling of 18810421 in words is "eighteen million, eight hundred ten thousand, four hundred twenty-one".