21442320421 has 4 divisors (see below), whose sum is σ = 21444270732. Its totient is φ = 21440370112.

The previous prime is 21442320413. The next prime is 21442320443. The reversal of 21442320421 is 12402324412.

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 2969705025 + 18472615396 = 54495^2 + 135914^2 .

It is a cyclic number.

It is not a de Polignac number, because 21442320421 - 2³ = 21442320413 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 (21442320481) 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 in 3 ways as a sum of consecutive naturals, for example, 958570 + ... + 980683.

It is an arithmetic number, because the mean of its divisors is an integer number (5361067683).

Almost surely, 2^21442320421 is an apocalyptic number.

It is an amenable number.

21442320421 is a deficient number, since it is larger than the sum of its proper divisors (1950311).

21442320421 is a wasteful number, since it uses less digits than its factorization.

21442320421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1950310.

The product of its (nonzero) digits is 3072, while the sum is 25.

Adding to 21442320421 its reverse (12402324412), we get a palindrome (33844644833).

The spelling of 21442320421 in words is "twenty-one billion, four hundred forty-two million, three hundred twenty thousand, four hundred twenty-one".