21242233421 has 4 divisors (see below), whose sum is σ = 21643030332. Its totient is φ = 20841436512.

The previous prime is 21242233367. The next prime is 21242233423. The reversal of 21242233421 is 12433224212.

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 10042244521 + 11199988900 = 100211^2 + 105830^2 .

It is a cyclic number.

It is not a de Polignac number, because 21242233421 - 2⁶ = 21242233357 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21242233423) 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, 200398376 + ... + 200398481.

It is an arithmetic number, because the mean of its divisors is an integer number (5410757583).

Almost surely, 2^21242233421 is an apocalyptic number.

It is an amenable number.

21242233421 is a deficient number, since it is larger than the sum of its proper divisors (400796911).

21242233421 is an equidigital number, since it uses as much as digits as its factorization.

21242233421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 400796910.

The product of its digits is 4608, while the sum is 26.

Adding to 21242233421 its reverse (12433224212), we get a palindrome (33675457633).

The spelling of 21242233421 in words is "twenty-one billion, two hundred forty-two million, two hundred thirty-three thousand, four hundred twenty-one".