21142431221 has 16 divisors (see below), whose sum is σ = 22029697536. Its totient is φ = 20276219376.

The previous prime is 21142431199. The next prime is 21142431229. The reversal of 21142431221 is 12213424112.

It is a cyclic number.

It is not a de Polignac number, because 21142431221 - 2²⁶ = 21075322357 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 (21142431229) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 563576 + ... + 599918.

It is an arithmetic number, because the mean of its divisors is an integer number (1376856096).

Almost surely, 2^21142431221 is an apocalyptic number.

It is an amenable number.

21142431221 is a deficient number, since it is larger than the sum of its proper divisors (887266315).

21142431221 is a wasteful number, since it uses less digits than its factorization.

21142431221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36632.

The product of its digits is 768, while the sum is 23.

Adding to 21142431221 its reverse (12213424112), we get a palindrome (33355855333).

The spelling of 21142431221 in words is "twenty-one billion, one hundred forty-two million, four hundred thirty-one thousand, two hundred twenty-one".