131981821 has 2 divisors, whose sum is σ = 131981822. Its totient is φ = 131981820.

The previous prime is 131981807. The next prime is 131981867. The reversal of 131981821 is 128189131.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 119661721 + 12320100 = 10939^2 + 3510^2 .

It is a cyclic number.

It is not a de Polignac number, because 131981821 - 2⁹ = 131981309 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (131981021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 65990910 + 65990911.

It is an arithmetic number, because the mean of its divisors is an integer number (65990911).

Almost surely, 2^131981821 is an apocalyptic number.

It is an amenable number.

131981821 is a deficient number, since it is larger than the sum of its proper divisors (1).

131981821 is an equidigital number, since it uses as much as digits as its factorization.

131981821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3456, while the sum is 34.

The square root of 131981821 is about 11488.3341264084. The cubic root of 131981821 is about 509.1409619068.

The spelling of 131981821 in words is "one hundred thirty-one million, nine hundred eighty-one thousand, eight hundred twenty-one".