21241224421 has 4 divisors (see below), whose sum is σ = 21532200172. Its totient is φ = 20950248672.

The previous prime is 21241224391. The next prime is 21241224437. The reversal of 21241224421 is 12442214212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6700241025 + 14540983396 = 81855^2 + 120586^2 .

It is a cyclic number.

It is not a de Polignac number, because 21241224421 - 2⁹ = 21241223909 is a prime.

It is a super-2 number, since 2×21241224421² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21241224451) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 145487766 + ... + 145487911.

It is an arithmetic number, because the mean of its divisors is an integer number (5383050043).

Almost surely, 2^21241224421 is an apocalyptic number.

It is an amenable number.

21241224421 is a deficient number, since it is larger than the sum of its proper divisors (290975751).

21241224421 is an equidigital number, since it uses as much as digits as its factorization.

21241224421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 290975750.

The product of its digits is 2048, while the sum is 25.

Adding to 21241224421 its reverse (12442214212), we get a palindrome (33683438633).

The spelling of 21241224421 in words is "twenty-one billion, two hundred forty-one million, two hundred twenty-four thousand, four hundred twenty-one".