131220421 has 4 divisors (see below), whose sum is σ = 133696332. Its totient is φ = 128744512.

The previous prime is 131220409. The next prime is 131220449. The reversal of 131220421 is 124022131.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 124022131 = 227 ⋅546353.

It can be written as a sum of positive squares in 2 ways, for example, as 32615521 + 98604900 = 5711^2 + 9930^2 .

It is a cyclic number.

It is not a de Polignac number, because 131220421 - 2⁷ = 131220293 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 131220395 and 131220404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (131220521) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1237876 + ... + 1237981.

It is an arithmetic number, because the mean of its divisors is an integer number (33424083).

Almost surely, 2^131220421 is an apocalyptic number.

It is an amenable number.

131220421 is a deficient number, since it is larger than the sum of its proper divisors (2475911).

131220421 is an equidigital number, since it uses as much as digits as its factorization.

131220421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2475910.

The product of its (nonzero) digits is 96, while the sum is 16.

The square root of 131220421 is about 11455.1482312539. The cubic root of 131220421 is about 508.1599990467.

Adding to 131220421 its reverse (124022131), we get a palindrome (255242552).

The spelling of 131220421 in words is "one hundred thirty-one million, two hundred twenty thousand, four hundred twenty-one".