11393981 has 4 divisors (see below), whose sum is σ = 11401692. Its totient is φ = 11386272.

The previous prime is 11393971. The next prime is 11393989. The reversal of 11393981 is 18939311.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 18939311 = 3001 ⋅6311.

It can be written as a sum of positive squares in 2 ways, for example, as 7513081 + 3880900 = 2741^2 + 1970^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-11393981 is a prime.

It is a super-2 number, since 2×11393981² = 259645606056722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11393989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 866 + ... + 4851.

It is an arithmetic number, because the mean of its divisors is an integer number (2850423).

Almost surely, 2^11393981 is an apocalyptic number.

It is an amenable number.

11393981 is a deficient number, since it is larger than the sum of its proper divisors (7711).

11393981 is an equidigital number, since it uses as much as digits as its factorization.

11393981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7710.

The product of its digits is 5832, while the sum is 35.

The square root of 11393981 is about 3375.4971485694. The cubic root of 11393981 is about 225.0220949496.

The spelling of 11393981 in words is "eleven million, three hundred ninety-three thousand, nine hundred eighty-one".