21120244421 has 2 divisors, whose sum is σ = 21120244422. Its totient is φ = 21120244420.

The previous prime is 21120244403. The next prime is 21120244459. The reversal of 21120244421 is 12444202112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19203030625 + 1917213796 = 138575^2 + 43786^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21120244421 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21120244471) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560122210 + 10560122211.

It is an arithmetic number, because the mean of its divisors is an integer number (10560122211).

Almost surely, 2^21120244421 is an apocalyptic number.

It is an amenable number.

21120244421 is a deficient number, since it is larger than the sum of its proper divisors (1).

21120244421 is an equidigital number, since it uses as much as digits as its factorization.

21120244421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1024, while the sum is 23.

Adding to 21120244421 its reverse (12444202112), we get a palindrome (33564446533).

The spelling of 21120244421 in words is "twenty-one billion, one hundred twenty million, two hundred forty-four thousand, four hundred twenty-one".