12131781 has 16 divisors (see below), whose sum is σ = 16665600. Its totient is φ = 7846128.

The previous prime is 12131771. The next prime is 12131789. The reversal of 12131781 is 18713121.

It is a happy number.

It is not a de Polignac number, because 12131781 - 2⁷ = 12131653 is a prime.

It is a super-2 number, since 2×12131781² = 294360220463922, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12131789) 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 15 ways as a sum of consecutive naturals, for example, 19290 + ... + 19908.

It is an arithmetic number, because the mean of its divisors is an integer number (1041600).

Almost surely, 2^12131781 is an apocalyptic number.

It is an amenable number.

12131781 is a deficient number, since it is larger than the sum of its proper divisors (4533819).

12131781 is a wasteful number, since it uses less digits than its factorization.

12131781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 808.

The product of its digits is 336, while the sum is 24.

The square root of 12131781 is about 3483.0706280522. The cubic root of 12131781 is about 229.7778636624. Note that the first 3 decimals are identical.

The spelling of 12131781 in words is "twelve million, one hundred thirty-one thousand, seven hundred eighty-one".