131091981 has 8 divisors (see below), whose sum is σ = 185071104. Its totient is φ = 82253760.

The previous prime is 131091971. The next prime is 131091991. The reversal of 131091981 is 189190131.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (131091971) and next prime (131091991).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 131091981 - 2⁷ = 131091853 is a prime.

It is a super-2 number, since 2×131091981² = 34370214965008722, which contains 22 as substring.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (131091941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1285165 + ... + 1285266.

It is an arithmetic number, because the mean of its divisors is an integer number (23133888).

Almost surely, 2^131091981 is an apocalyptic number.

It is an amenable number.

131091981 is a deficient number, since it is larger than the sum of its proper divisors (53979123).

131091981 is a wasteful number, since it uses less digits than its factorization.

131091981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2570451.

The product of its (nonzero) digits is 1944, while the sum is 33.

The square root of 131091981 is about 11449.5406458076. The cubic root of 131091981 is about 507.9941473792.

The spelling of 131091981 in words is "one hundred thirty-one million, ninety-one thousand, nine hundred eighty-one".