21242422261 has 2 divisors, whose sum is σ = 21242422262. Its totient is φ = 21242422260.

The previous prime is 21242422247. The next prime is 21242422273. The reversal of 21242422261 is 16222424212.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19322668036 + 1919754225 = 139006^2 + 43815^2 .

It is a cyclic number.

It is not a de Polignac number, because 21242422261 - 2¹⁹ = 21241897973 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21242428261) 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, 10621211130 + 10621211131.

It is an arithmetic number, because the mean of its divisors is an integer number (10621211131).

Almost surely, 2^21242422261 is an apocalyptic number.

It is an amenable number.

21242422261 is a deficient number, since it is larger than the sum of its proper divisors (1).

21242422261 is an equidigital number, since it uses as much as digits as its factorization.

21242422261 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6144, while the sum is 28.

Adding to 21242422261 its reverse (16222424212), we get a palindrome (37464846473).

The spelling of 21242422261 in words is "twenty-one billion, two hundred forty-two million, four hundred twenty-two thousand, two hundred sixty-one".