131487781 has 4 divisors (see below), whose sum is σ = 131580972. Its totient is φ = 131394592.

The previous prime is 131487773. The next prime is 131487821. The reversal of 131487781 is 187784131.

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 118048225 + 13439556 = 10865^2 + 3666^2 .

It is a cyclic number.

It is not a de Polignac number, because 131487781 - 2³ = 131487773 is a prime.

It is a super-2 number, since 2×131487781² = 34578073104607922, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (131487761) 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, 44446 + ... + 47311.

It is an arithmetic number, because the mean of its divisors is an integer number (32895243).

Almost surely, 2^131487781 is an apocalyptic number.

It is an amenable number.

131487781 is a deficient number, since it is larger than the sum of its proper divisors (93191).

131487781 is an equidigital number, since it uses as much as digits as its factorization.

131487781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 93190.

The product of its digits is 37632, while the sum is 40.

The square root of 131487781 is about 11466.8121550848. The cubic root of 131487781 is about 508.5048881741.

The spelling of 131487781 in words is "one hundred thirty-one million, four hundred eighty-seven thousand, seven hundred eighty-one".