131181821 has 4 divisors (see below), whose sum is σ = 132017532. Its totient is φ = 130346112.

The previous prime is 131181797. The next prime is 131181829. The reversal of 131181821 is 128181131.

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 19456921 + 111724900 = 4411^2 + 10570^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-131181821 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (131181829) 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, 417620 + ... + 417933.

It is an arithmetic number, because the mean of its divisors is an integer number (33004383).

Almost surely, 2^131181821 is an apocalyptic number.

It is an amenable number.

131181821 is a deficient number, since it is larger than the sum of its proper divisors (835711).

131181821 is an equidigital number, since it uses as much as digits as its factorization.

131181821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 835710.

The product of its digits is 384, while the sum is 26.

The square root of 131181821 is about 11453.4632753591. The cubic root of 131181821 is about 508.1101671190.

The spelling of 131181821 in words is "one hundred thirty-one million, one hundred eighty-one thousand, eight hundred twenty-one".