2131223221 has 4 divisors (see below), whose sum is σ = 2131323372. Its totient is φ = 2131123072.

The previous prime is 2131223219. The next prime is 2131223239. The reversal of 2131223221 is 1223221312.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 1407075121 + 724148100 = 37511^2 + 26910^2 .

It is a cyclic number.

It is not a de Polignac number, because 2131223221 - 2¹ = 2131223219 is a prime.

It is a super-2 number, since 2×2131223221² = 9084224835459229682, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2131223201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4060 + ... + 65413.

It is an arithmetic number, because the mean of its divisors is an integer number (532830843).

Almost surely, 2^2131223221 is an apocalyptic number.

It is an amenable number.

2131223221 is a deficient number, since it is larger than the sum of its proper divisors (100151).

2131223221 is an equidigital number, since it uses as much as digits as its factorization.

2131223221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 100150.

The product of its digits is 288, while the sum is 19.

The square root of 2131223221 is about 46165.1732478066. The cubic root of 2131223221 is about 1286.8946038215.

Adding to 2131223221 its reverse (1223221312), we get a palindrome (3354444533).

The spelling of 2131223221 in words is "two billion, one hundred thirty-one million, two hundred twenty-three thousand, two hundred twenty-one".