131531221 has 2 divisors, whose sum is σ = 131531222. Its totient is φ = 131531220.

The previous prime is 131531207. The next prime is 131531249. The reversal of 131531221 is 122135131.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 85100625 + 46430596 = 9225^2 + 6814^2 .

It is an emirp because it is prime and its reverse (122135131) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 131531221 - 2⁷ = 131531093 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (131531201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 65765610 + 65765611.

It is an arithmetic number, because the mean of its divisors is an integer number (65765611).

Almost surely, 2^131531221 is an apocalyptic number.

It is an amenable number.

131531221 is a deficient number, since it is larger than the sum of its proper divisors (1).

131531221 is an equidigital number, since it uses as much as digits as its factorization.

131531221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 180, while the sum is 19.

The square root of 131531221 is about 11468.7061606792. The cubic root of 131531221 is about 508.5608807539.

Adding to 131531221 its reverse (122135131), we get a palindrome (253666352).

The spelling of 131531221 in words is "one hundred thirty-one million, five hundred thirty-one thousand, two hundred twenty-one".