11981831 has 2 divisors, whose sum is σ = 11981832. Its totient is φ = 11981830.

The previous prime is 11981813. The next prime is 11981833. The reversal of 11981831 is 13818911.

11981831 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

Together with previous prime (11981813) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 11981831 - 2¹⁰ = 11980807 is a prime.

It is a super-2 number, since 2×11981831² = 287128548225122, which contains 22 as substring.

Together with 11981833, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (11981833) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5990915 + 5990916.

It is an arithmetic number, because the mean of its divisors is an integer number (5990916).

Almost surely, 2^11981831 is an apocalyptic number.

11981831 is a deficient number, since it is larger than the sum of its proper divisors (1).

11981831 is an equidigital number, since it uses as much as digits as its factorization.

11981831 is an evil number, because the sum of its binary digits is even.

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

The square root of 11981831 is about 3461.4781524661. The cubic root of 11981831 is about 228.8272439623.

The spelling of 11981831 in words is "eleven million, nine hundred eighty-one thousand, eight hundred thirty-one".