19964821 has 2 divisors, whose sum is σ = 19964822. Its totient is φ = 19964820.

The previous prime is 19964803. The next prime is 19964849. The reversal of 19964821 is 12846991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19704721 + 260100 = 4439^2 + 510^2 .

It is an emirp because it is prime and its reverse (12846991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19964821 - 2²¹ = 17867669 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 (19964881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9982410 + 9982411.

It is an arithmetic number, because the mean of its divisors is an integer number (9982411).

Almost surely, 2^19964821 is an apocalyptic number.

It is an amenable number.

19964821 is a deficient number, since it is larger than the sum of its proper divisors (1).

19964821 is an equidigital number, since it uses as much as digits as its factorization.

19964821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 31104, while the sum is 40.

The square root of 19964821 is about 4468.2010921623. The cubic root of 19964821 is about 271.2825174265.

The spelling of 19964821 in words is "nineteen million, nine hundred sixty-four thousand, eight hundred twenty-one".