21144012221 has 16 divisors (see below), whose sum is σ = 21419545728. Its totient is φ = 20870784000.

The previous prime is 21144012203. The next prime is 21144012233. The reversal of 21144012221 is 12221044112.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21144012221 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21144012193 and 21144012202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21144012521) 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, 21641285 + ... + 21642261.

It is an arithmetic number, because the mean of its divisors is an integer number (1338721608).

Almost surely, 2^21144012221 is an apocalyptic number.

It is an amenable number.

21144012221 is a deficient number, since it is larger than the sum of its proper divisors (275533507).

21144012221 is a wasteful number, since it uses less digits than its factorization.

21144012221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1892.

The product of its (nonzero) digits is 256, while the sum is 20.

Adding to 21144012221 its reverse (12221044112), we get a palindrome (33365056333).

The spelling of 21144012221 in words is "twenty-one billion, one hundred forty-four million, twelve thousand, two hundred twenty-one".