19388021 has 2 divisors, whose sum is σ = 19388022. Its totient is φ = 19388020.

The previous prime is 19388003. The next prime is 19388059. The reversal of 19388021 is 12088391.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11764900 + 7623121 = 3430^2 + 2761^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19388021 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19388071) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9694010 + 9694011.

It is an arithmetic number, because the mean of its divisors is an integer number (9694011).

Almost surely, 2^19388021 is an apocalyptic number.

It is an amenable number.

19388021 is a deficient number, since it is larger than the sum of its proper divisors (1).

19388021 is an equidigital number, since it uses as much as digits as its factorization.

19388021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3456, while the sum is 32.

The square root of 19388021 is about 4403.1830532014. The cubic root of 19388021 is about 268.6444217705.

The spelling of 19388021 in words is "nineteen million, three hundred eighty-eight thousand, twenty-one".