19839421 has 4 divisors (see below), whose sum is σ = 22673632. Its totient is φ = 17005212.

The previous prime is 19839373. The next prime is 19839427. The reversal of 19839421 is 12493891.

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 not a de Polignac number, because 19839421 - 2¹⁵ = 19806653 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 (19839427) 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, 1417095 + ... + 1417108.

It is an arithmetic number, because the mean of its divisors is an integer number (5668408).

Almost surely, 2^19839421 is an apocalyptic number.

It is an amenable number.

19839421 is a deficient number, since it is larger than the sum of its proper divisors (2834211).

19839421 is an equidigital number, since it uses as much as digits as its factorization.

19839421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2834210.

The product of its digits is 15552, while the sum is 37.

The square root of 19839421 is about 4454.1464951211. The cubic root of 19839421 is about 270.7133445817.

The spelling of 19839421 in words is "nineteen million, eight hundred thirty-nine thousand, four hundred twenty-one".