131431221 has 8 divisors (see below), whose sum is σ = 194712960. Its totient is φ = 87620796.

The previous prime is 131431213. The next prime is 131431231. The reversal of 131431221 is 122134131.

131431221 is a `hidden beast` number, since 13 + 1 + 431 + 221 = 666.

It is not a de Polignac number, because 131431221 - 2³ = 131431213 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 131431194 and 131431203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (131431211) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2433885 + ... + 2433938.

It is an arithmetic number, because the mean of its divisors is an integer number (24339120).

Almost surely, 2^131431221 is an apocalyptic number.

It is an amenable number.

131431221 is a deficient number, since it is larger than the sum of its proper divisors (63281739).

131431221 is an equidigital number, since it uses as much as digits as its factorization.

131431221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4867832 (or 4867826 counting only the distinct ones).

The product of its digits is 144, while the sum is 18.

The square root of 131431221 is about 11464.3456420330. The cubic root of 131431221 is about 508.4319659068.

Adding to 131431221 its reverse (122134131), we get a palindrome (253565352).

The spelling of 131431221 in words is "one hundred thirty-one million, four hundred thirty-one thousand, two hundred twenty-one".