131221328 has 20 divisors (see below), whose sum is σ = 290561760. Its totient is φ = 56237664.

The previous prime is 131221327. The next prime is 131221339. The reversal of 131221328 is 823122131.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (131221327) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 585698 + ... + 585921.

It is an arithmetic number, because the mean of its divisors is an integer number (14528088).

Almost surely, 2^131221328 is an apocalyptic number.

It is an amenable number.

131221328 is an abundant number, since it is smaller than the sum of its proper divisors (159340432).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

131221328 is a wasteful number, since it uses less digits than its factorization.

131221328 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1171634 (or 1171628 counting only the distinct ones).

The product of its digits is 576, while the sum is 23.

The square root of 131221328 is about 11455.1878203720. The cubic root of 131221328 is about 508.1611698504.

Adding to 131221328 its reverse (823122131), we get a palindrome (954343459).

The spelling of 131221328 in words is "one hundred thirty-one million, two hundred twenty-one thousand, three hundred twenty-eight".