19794821 has 2 divisors, whose sum is σ = 19794822. Its totient is φ = 19794820.

The previous prime is 19794809. The next prime is 19794823. The reversal of 19794821 is 12849791.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17724100 + 2070721 = 4210^2 + 1439^2 .

It is an emirp because it is prime and its reverse (12849791) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19794821 is a prime.

Together with 19794823, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19794823) 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, 9897410 + 9897411.

It is an arithmetic number, because the mean of its divisors is an integer number (9897411).

Almost surely, 2^19794821 is an apocalyptic number.

It is an amenable number.

19794821 is a deficient number, since it is larger than the sum of its proper divisors (1).

19794821 is an equidigital number, since it uses as much as digits as its factorization.

19794821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 36288, while the sum is 41.

The square root of 19794821 is about 4449.1371073501. The cubic root of 19794821 is about 270.5103333816.

The spelling of 19794821 in words is "nineteen million, seven hundred ninety-four thousand, eight hundred twenty-one".