131801981 has 4 divisors (see below), whose sum is σ = 131850972. Its totient is φ = 131752992.

The previous prime is 131801947. The next prime is 131802017. The reversal of 131801981 is 189108131.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 189108131 = 3221 ⋅58711.

It can be written as a sum of positive squares in 2 ways, for example, as 83429956 + 48372025 = 9134^2 + 6955^2 .

It is a cyclic number.

It is not a de Polignac number, because 131801981 - 2¹⁴ = 131785597 is a prime.

It is a super-2 number, since 2×131801981² = 34743524391048722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (131806981) 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, 20210 + ... + 25923.

It is an arithmetic number, because the mean of its divisors is an integer number (32962743).

Almost surely, 2^131801981 is an apocalyptic number.

It is an amenable number.

131801981 is a deficient number, since it is larger than the sum of its proper divisors (48991).

131801981 is an equidigital number, since it uses as much as digits as its factorization.

131801981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48990.

The product of its (nonzero) digits is 1728, while the sum is 32.

The square root of 131801981 is about 11480.5043878743. The cubic root of 131801981 is about 508.9096029461.

The spelling of 131801981 in words is "one hundred thirty-one million, eight hundred one thousand, nine hundred eighty-one".