19824421 has 4 divisors (see below), whose sum is σ = 19834732. Its totient is φ = 19814112.

The previous prime is 19824379. The next prime is 19824437. The reversal of 19824421 is 12442891.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 12442891 = 19 ⋅654889.

It can be written as a sum of positive squares in 2 ways, for example, as 15880225 + 3944196 = 3985^2 + 1986^2 .

It is a cyclic number.

It is not a de Polignac number, because 19824421 - 2⁷ = 19824293 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 (19824461) 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, 1320 + ... + 6433.

It is an arithmetic number, because the mean of its divisors is an integer number (4958683).

Almost surely, 2^19824421 is an apocalyptic number.

It is an amenable number.

19824421 is a deficient number, since it is larger than the sum of its proper divisors (10311).

19824421 is an equidigital number, since it uses as much as digits as its factorization.

19824421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10310.

The product of its digits is 4608, while the sum is 31.

The square root of 19824421 is about 4452.4623524517. The cubic root of 19824421 is about 270.6451012596.

The spelling of 19824421 in words is "nineteen million, eight hundred twenty-four thousand, four hundred twenty-one".