21421442197 has 2 divisors, whose sum is σ = 21421442198. Its totient is φ = 21421442196.

The previous prime is 21421442183. The next prime is 21421442227. The reversal of 21421442197 is 79124412412.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17110994481 + 4310447716 = 130809^2 + 65654^2 .

It is a cyclic number.

It is not a de Polignac number, because 21421442197 - 2¹⁹ = 21420917909 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21421442167) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10710721098 + 10710721099.

It is an arithmetic number, because the mean of its divisors is an integer number (10710721099).

Almost surely, 2^21421442197 is an apocalyptic number.

It is an amenable number.

21421442197 is a deficient number, since it is larger than the sum of its proper divisors (1).

21421442197 is an equidigital number, since it uses as much as digits as its factorization.

21421442197 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 32256, while the sum is 37.

The spelling of 21421442197 in words is "twenty-one billion, four hundred twenty-one million, four hundred forty-two thousand, one hundred ninety-seven".