19819421 has 2 divisors, whose sum is σ = 19819422. Its totient is φ = 19819420.

The previous prime is 19819391. The next prime is 19819453. The reversal of 19819421 is 12491891.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12040900 + 7778521 = 3470^2 + 2789^2 .

It is a cyclic number.

It is not a de Polignac number, because 19819421 - 2⁶ = 19819357 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19819621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9909710 + 9909711.

It is an arithmetic number, because the mean of its divisors is an integer number (9909711).

Almost surely, 2^19819421 is an apocalyptic number.

It is an amenable number.

19819421 is a deficient number, since it is larger than the sum of its proper divisors (1).

19819421 is an equidigital number, since it uses as much as digits as its factorization.

19819421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5184, while the sum is 35.

The square root of 19819421 is about 4451.9008299826. The cubic root of 19819421 is about 270.6223458360.

The spelling of 19819421 in words is "nineteen million, eight hundred nineteen thousand, four hundred twenty-one".