131211212221 has 4 divisors (see below), whose sum is σ = 131215121532. Its totient is φ = 131207302912.

The previous prime is 131211212189. The next prime is 131211212227. The reversal of 131211212221 is 122212112131.

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 102151191321 + 29060020900 = 319611^2 + 170470^2 .

It is a cyclic number.

It is not a de Polignac number, because 131211212221 - 2⁵ = 131211212189 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 (131211212227) 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, 1903870 + ... + 1971583.

It is an arithmetic number, because the mean of its divisors is an integer number (32803780383).

Almost surely, 2^131211212221 is an apocalyptic number.

It is an amenable number.

131211212221 is a deficient number, since it is larger than the sum of its proper divisors (3909311).

131211212221 is an equidigital number, since it uses as much as digits as its factorization.

131211212221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3909310.

The product of its digits is 96, while the sum is 19.

Adding to 131211212221 its reverse (122212112131), we get a palindrome (253423324352).

The spelling of 131211212221 in words is "one hundred thirty-one billion, two hundred eleven million, two hundred twelve thousand, two hundred twenty-one".