21401424221 has 4 divisors (see below), whose sum is σ = 21805224732. Its totient is φ = 20997623712.

The previous prime is 21401424127. The next prime is 21401424223. The reversal of 21401424221 is 12242410412.

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 17886120121 + 3515304100 = 133739^2 + 59290^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21401424221 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 (21401424223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 201900176 + ... + 201900281.

It is an arithmetic number, because the mean of its divisors is an integer number (5451306183).

Almost surely, 2^21401424221 is an apocalyptic number.

It is an amenable number.

21401424221 is a deficient number, since it is larger than the sum of its proper divisors (403800511).

21401424221 is an equidigital number, since it uses as much as digits as its factorization.

21401424221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 403800510.

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

Adding to 21401424221 its reverse (12242410412), we get a palindrome (33643834633).

The spelling of 21401424221 in words is "twenty-one billion, four hundred one million, four hundred twenty-four thousand, two hundred twenty-one".