19421 has 2 divisors, whose sum is σ = 19422. Its totient is φ = 19420.

The previous prime is 19417. The next prime is 19423. The reversal of 19421 is 12491.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19321 + 100 = 139^2 + 10^2 .

It is an emirp because it is prime and its reverse (12491) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19421 - 2² = 19417 is a prime.

Together with 19423, it forms a pair of twin primes.

It is a Chen prime.

It is a plaindrome in base 13 and base 16.

It is a self number, because there is not a number n which added to its sum of digits gives 19421.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19423) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9710 + 9711.

It is an arithmetic number, because the mean of its divisors is an integer number (9711).

2¹⁹⁴²¹ is an apocalyptic number.

It is an amenable number.

19421 is a deficient number, since it is larger than the sum of its proper divisors (1).

19421 is an equidigital number, since it uses as much as digits as its factorization.

19421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 72, while the sum is 17.

The square root of 19421 is about 139.3592479888. The cubic root of 19421 is about 26.8796656764.

The spelling of 19421 in words is "nineteen thousand, four hundred twenty-one".