11509681 has 4 divisors (see below), whose sum is σ = 11777392. Its totient is φ = 11241972.

The previous prime is 11509679. The next prime is 11509727. The reversal of 11509681 is 18690511.

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 11509681 - 2¹ = 11509679 is a prime.

It is a super-2 number, since 2×11509681² = 264945513443522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11509621) 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, 133791 + ... + 133876.

It is an arithmetic number, because the mean of its divisors is an integer number (2944348).

Almost surely, 2^11509681 is an apocalyptic number.

It is an amenable number.

11509681 is a deficient number, since it is larger than the sum of its proper divisors (267711).

11509681 is an equidigital number, since it uses as much as digits as its factorization.

11509681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 267710.

The product of its (nonzero) digits is 2160, while the sum is 31.

The square root of 11509681 is about 3392.5920768639. The cubic root of 11509681 is about 225.7811924063.

The spelling of 11509681 in words is "eleven million, five hundred nine thousand, six hundred eighty-one".