21013031221 has 16 divisors (see below), whose sum is σ = 25913059200. Its totient is φ = 16592995008.

The previous prime is 21013031161. The next prime is 21013031243. The reversal of 21013031221 is 12213031012.

It is a cyclic number.

It is not a de Polignac number, because 21013031221 - 2¹⁷ = 21012900149 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21013031195 and 21013031204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21013031261) 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, 180511 + ... + 273148.

It is an arithmetic number, because the mean of its divisors is an integer number (1619566200).

Almost surely, 2^21013031221 is an apocalyptic number.

It is an amenable number.

21013031221 is a deficient number, since it is larger than the sum of its proper divisors (4900027979).

21013031221 is a wasteful number, since it uses less digits than its factorization.

21013031221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 454188.

The product of its (nonzero) digits is 72, while the sum is 16.

Adding to 21013031221 its reverse (12213031012), we get a palindrome (33226062233).

The spelling of 21013031221 in words is "twenty-one billion, thirteen million, thirty-one thousand, two hundred twenty-one".