1131981 has 4 divisors (see below), whose sum is σ = 1509312. Its totient is φ = 754652.

The previous prime is 1131973. The next prime is 1131997. The reversal of 1131981 is 1891311.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1131981 - 2³ = 1131973 is a prime.

It is a super-2 number, since 2×1131981² = 2562761968722, which contains 22 as substring.

It is a D-number.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1131961) 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, 188661 + ... + 188666.

It is an arithmetic number, because the mean of its divisors is an integer number (377328).

2^1131981 is an apocalyptic number.

It is an amenable number.

1131981 is a deficient number, since it is larger than the sum of its proper divisors (377331).

1131981 is an equidigital number, since it uses as much as digits as its factorization.

1131981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 377330.

The product of its digits is 216, while the sum is 24.

The square root of 1131981 is about 1063.9459572741. The cubic root of 1131981 is about 104.2188745937.

It can be divided in two parts, 1131 and 981, that added together give a palindrome (2112).

The spelling of 1131981 in words is "one million, one hundred thirty-one thousand, nine hundred eighty-one".