131220121 has 4 divisors (see below), whose sum is σ = 131900212. Its totient is φ = 130540032.

The previous prime is 131220101. The next prime is 131220143. The reversal of 131220121 is 121022131.

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 13801225 + 117418896 = 3715^2 + 10836^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-131220121 is a prime.

It is a super-3 number, since 3×131220121³ (a number of 25 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (131220101) 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, 339756 + ... + 340141.

It is an arithmetic number, because the mean of its divisors is an integer number (32975053).

Almost surely, 2^131220121 is an apocalyptic number.

It is an amenable number.

131220121 is a deficient number, since it is larger than the sum of its proper divisors (680091).

131220121 is an equidigital number, since it uses as much as digits as its factorization.

131220121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 680090.

The product of its (nonzero) digits is 24, while the sum is 13.

The square root of 131220121 is about 11455.1351366974. The cubic root of 131220121 is about 508.1596117896.

Adding to 131220121 its reverse (121022131), we get a palindrome (252242252).

The spelling of 131220121 in words is "one hundred thirty-one million, two hundred twenty thousand, one hundred twenty-one".