11728781 has 4 divisors (see below), whose sum is σ = 12238752. Its totient is φ = 11218812.

The previous prime is 11728777. The next prime is 11728799. The reversal of 11728781 is 18782711.

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, and also an emirpimes, since its reverse is a distinct semiprime: 18782711 = 1789 ⋅10499.

It is a cyclic number.

It is not a de Polignac number, because 11728781 - 2² = 11728777 is a prime.

It is a super-2 number, since 2×11728781² = 275128607491922, 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 (11728721) 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, 254951 + ... + 254996.

It is an arithmetic number, because the mean of its divisors is an integer number (3059688).

Almost surely, 2^11728781 is an apocalyptic number.

It is an amenable number.

11728781 is a deficient number, since it is larger than the sum of its proper divisors (509971).

11728781 is an equidigital number, since it uses as much as digits as its factorization.

11728781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 509970.

The product of its digits is 6272, while the sum is 35.

The square root of 11728781 is about 3424.7307923397. The cubic root of 11728781 is about 227.2048646404.

The spelling of 11728781 in words is "eleven million, seven hundred twenty-eight thousand, seven hundred eighty-one".