21311313122221 has 4 divisors (see below), whose sum is σ = 21454342069500. Its totient is φ = 21168284174944.

The previous prime is 21311313122201. The next prime is 21311313122227. The reversal of 21311313122221 is 12222131311312.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1028774061225 + 20282539060996 = 1014285^2 + 4503614^2 .

It is a cyclic number.

It is not a de Polignac number, because 21311313122221 - 2³⁹ = 20761557308333 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 (21311313122227) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 71514473416 + ... + 71514473713.

It is an arithmetic number, because the mean of its divisors is an integer number (5363585517375).

Almost surely, 2^{21311313122221} is an apocalyptic number.

It is an amenable number.

21311313122221 is a deficient number, since it is larger than the sum of its proper divisors (143028947279).

21311313122221 is a wasteful number, since it uses less digits than its factorization.

21311313122221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 143028947278.

The product of its digits is 864, while the sum is 25.

Adding to 21311313122221 its reverse (12222131311312), we get a palindrome (33533444433533).

The spelling of 21311313122221 in words is "twenty-one trillion, three hundred eleven billion, three hundred thirteen million, one hundred twenty-two thousand, two hundred twenty-one".