21423229981 has 2 divisors, whose sum is σ = 21423229982. Its totient is φ = 21423229980.

The previous prime is 21423229973. The next prime is 21423230053. The reversal of 21423229981 is 18992232412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16677397881 + 4745832100 = 129141^2 + 68890^2 .

It is a cyclic number.

It is not a de Polignac number, because 21423229981 - 2³ = 21423229973 is a prime.

It is a super-2 number, since 2×21423229981² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21423229931) 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, 10711614990 + 10711614991.

It is an arithmetic number, because the mean of its divisors is an integer number (10711614991).

Almost surely, 2^21423229981 is an apocalyptic number.

It is an amenable number.

21423229981 is a deficient number, since it is larger than the sum of its proper divisors (1).

21423229981 is an equidigital number, since it uses as much as digits as its factorization.

21423229981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 124416, while the sum is 43.

The spelling of 21423229981 in words is "twenty-one billion, four hundred twenty-three million, two hundred twenty-nine thousand, nine hundred eighty-one".