11787981 has 4 divisors (see below), whose sum is σ = 15717312. Its totient is φ = 7858652.

The previous prime is 11787959. The next prime is 11787991. The reversal of 11787981 is 18978711.

It is a happy number.

11787981 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

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: 18978711 = 3 ⋅6326237.

It is a cyclic number.

It is not a de Polignac number, because 11787981 - 2⁹ = 11787469 is a prime.

It is a super-2 number, since 2×11787981² = 277912992112722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11787901) 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, 1964661 + ... + 1964666.

It is an arithmetic number, because the mean of its divisors is an integer number (3929328).

Almost surely, 2^11787981 is an apocalyptic number.

It is an amenable number.

11787981 is a deficient number, since it is larger than the sum of its proper divisors (3929331).

11787981 is an equidigital number, since it uses as much as digits as its factorization.

11787981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3929330.

The product of its digits is 28224, while the sum is 42.

The square root of 11787981 is about 3433.3629286750. The cubic root of 11787981 is about 227.5864888719.

The spelling of 11787981 in words is "eleven million, seven hundred eighty-seven thousand, nine hundred eighty-one".