131387781 has 24 divisors (see below), whose sum is σ = 212689600. Its totient is φ = 70659072.

The previous prime is 131387779. The next prime is 131387783. The reversal of 131387781 is 187783131.

It is an interprime number because it is at equal distance from previous prime (131387779) and next prime (131387783).

It is not a de Polignac number, because 131387781 - 2¹ = 131387779 is a prime.

It is a super-2 number, since 2×131387781² = 34525497992207922, which contains 22 as substring.

It is a Duffinian 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 (131387783) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4756 + ... + 16893.

Almost surely, 2^131387781 is an apocalyptic number.

It is an amenable number.

131387781 is a deficient number, since it is larger than the sum of its proper divisors (81301819).

131387781 is a wasteful number, since it uses less digits than its factorization.

131387781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21693 (or 21676 counting only the distinct ones).

The product of its digits is 28224, while the sum is 39.

The square root of 131387781 is about 11462.4509159254. The cubic root of 131387781 is about 508.3759449245.

The spelling of 131387781 in words is "one hundred thirty-one million, three hundred eighty-seven thousand, seven hundred eighty-one".