21311321012221 has 32 divisors (see below), whose sum is σ = 22076466203232. Its totient is φ = 20561396244480.

The previous prime is 21311321012207. The next prime is 21311321012249. The reversal of 21311321012221 is 12221012311312.

It is a happy number.

It can be written as a sum of positive squares in 16 ways, for example, as 5096243040196 + 16215077972025 = 2257486^2 + 4026795^2 .

It is a cyclic number.

It is not a de Polignac number, because 21311321012221 - 2⁹ = 21311321011709 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21311321012192 and 21311321012201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21311321013221) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3238307151 + ... + 3238313731.

It is an arithmetic number, because the mean of its divisors is an integer number (689889568851).

Almost surely, 2^{21311321012221} is an apocalyptic number.

It is an amenable number.

21311321012221 is a deficient number, since it is larger than the sum of its proper divisors (765145191011).

21311321012221 is a wasteful number, since it uses less digits than its factorization.

21311321012221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9073.

The product of its (nonzero) digits is 288, while the sum is 22.

Adding to 21311321012221 its reverse (12221012311312), we get a palindrome (33532333323533).

The spelling of 21311321012221 in words is "twenty-one trillion, three hundred eleven billion, three hundred twenty-one million, twelve thousand, two hundred twenty-one".