131223531 has 4 divisors (see below), whose sum is σ = 174964712. Its totient is φ = 87482352.

The previous prime is 131223517. The next prime is 131223539. The reversal of 131223531 is 135322131.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 131223531 - 2⁹ = 131223019 is a prime.

It is a super-2 number, since 2×131223531² = 34439230176215922, 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 = 131223498 and 131223507.

It is not an unprimeable number, because it can be changed into a prime (131223539) 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, 21870586 + ... + 21870591.

It is an arithmetic number, because the mean of its divisors is an integer number (43741178).

Almost surely, 2^131223531 is an apocalyptic number.

131223531 is a deficient number, since it is larger than the sum of its proper divisors (43741181).

131223531 is an equidigital number, since it uses as much as digits as its factorization.

131223531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43741180.

The product of its digits is 540, while the sum is 21.

The square root of 131223531 is about 11455.2839772744. The cubic root of 131223531 is about 508.1640135771.

Adding to 131223531 its reverse (135322131), we get a palindrome (266545662).

It can be divided in two parts, 13122 and 3531, that added together give a triangular number (16653 = T₁₈₂).

The spelling of 131223531 in words is "one hundred thirty-one million, two hundred twenty-three thousand, five hundred thirty-one".