11309981 has 4 divisors (see below), whose sum is σ = 11975292. Its totient is φ = 10644672.

The previous prime is 11309953. The next prime is 11309999. The reversal of 11309981 is 18990311.

11309981 = T₁₁₄₅ + T₁₁₄₆ + ... + T₁₁₆₁.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6175225 + 5134756 = 2485^2 + 2266^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-11309981 is a prime.

It is a super-2 number, since 2×11309981² = 255831340440722, 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 (11309911) 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 3 ways as a sum of consecutive naturals, for example, 332630 + ... + 332663.

It is an arithmetic number, because the mean of its divisors is an integer number (2993823).

Almost surely, 2^11309981 is an apocalyptic number.

It is an amenable number.

11309981 is a deficient number, since it is larger than the sum of its proper divisors (665311).

11309981 is an equidigital number, since it uses as much as digits as its factorization.

11309981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 665310.

The product of its (nonzero) digits is 1944, while the sum is 32.

The square root of 11309981 is about 3363.0315193290. The cubic root of 11309981 is about 224.4677526379.

It can be divided in two parts, 1130 and 9981, that added together give a palindrome (11111).

The spelling of 11309981 in words is "eleven million, three hundred nine thousand, nine hundred eighty-one".