8194420021 has 2 divisors, whose sum is σ = 8194420022. Its totient is φ = 8194420020.

The previous prime is 8194420009. The next prime is 8194420027. The reversal of 8194420021 is 1200244918.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6628239396 + 1566180625 = 81414^2 + 39575^2 .

It is a cyclic number.

It is not a de Polignac number, because 8194420021 - 2²¹ = 8192322869 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8194420027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4097210010 + 4097210011.

It is an arithmetic number, because the mean of its divisors is an integer number (4097210011).

Almost surely, 2^8194420021 is an apocalyptic number.

It is an amenable number.

8194420021 is a deficient number, since it is larger than the sum of its proper divisors (1).

8194420021 is an equidigital number, since it uses as much as digits as its factorization.

8194420021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4608, while the sum is 31.

The square root of 8194420021 is about 90523.0358582831. The cubic root of 8194420021 is about 2016.0721651968.

Adding to 8194420021 its reverse (1200244918), we get a palindrome (9394664939).

The spelling of 8194420021 in words is "eight billion, one hundred ninety-four million, four hundred twenty thousand, twenty-one".