21013041221 has 16 divisors (see below), whose sum is σ = 21842862384. Its totient is φ = 20198191104.

The previous prime is 21013041191. The next prime is 21013041349. The reversal of 21013041221 is 12214031012.

It can be written as a sum of positive squares in 8 ways, for example, as 4357848196 + 16655193025 = 66014^2 + 129055^2 .

It is a cyclic number.

It is not a de Polignac number, because 21013041221 - 2⁶ = 21013041157 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21013041221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21013041521) 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, 1300625 + ... + 1316681.

It is an arithmetic number, because the mean of its divisors is an integer number (1365178899).

Almost surely, 2^21013041221 is an apocalyptic number.

It is an amenable number.

21013041221 is a deficient number, since it is larger than the sum of its proper divisors (829821163).

21013041221 is a wasteful number, since it uses less digits than its factorization.

21013041221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16520.

The product of its (nonzero) digits is 96, while the sum is 17.

Adding to 21013041221 its reverse (12214031012), we get a palindrome (33227072233).

The spelling of 21013041221 in words is "twenty-one billion, thirteen million, forty-one thousand, two hundred twenty-one".