131221031 has 4 divisors (see below), whose sum is σ = 132026232. Its totient is φ = 130415832.

The previous prime is 131221021. The next prime is 131221037. The reversal of 131221031 is 130122131.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 130122131 = 17 ⋅7654243.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-131221031 is a prime.

It is a super-2 number, since 2×131221031² = 34437917953405922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 131220997 and 131221015.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (131221037) 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, 402356 + ... + 402681.

It is an arithmetic number, because the mean of its divisors is an integer number (33006558).

Almost surely, 2^131221031 is an apocalyptic number.

131221031 is a deficient number, since it is larger than the sum of its proper divisors (805201).

131221031 is an equidigital number, since it uses as much as digits as its factorization.

131221031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 805200.

The product of its (nonzero) digits is 36, while the sum is 14.

The square root of 131221031 is about 11455.1748568060. The cubic root of 131221031 is about 508.1607864676.

Adding to 131221031 its reverse (130122131), we get a palindrome (261343162).

The spelling of 131221031 in words is "one hundred thirty-one million, two hundred twenty-one thousand, thirty-one".