11771991 has 24 divisors (see below), whose sum is σ = 21201024. Its totient is φ = 6114960.

The previous prime is 11771983. The next prime is 11772029. The reversal of 11771991 is 19917711.

11771991 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 11771991 - 2³ = 11771983 is a prime.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11772991) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7801 + ... + 9186.

It is an arithmetic number, because the mean of its divisors is an integer number (883376).

Almost surely, 2^11771991 is an apocalyptic number.

11771991 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

11771991 is a deficient number, since it is larger than the sum of its proper divisors (9429033).

11771991 is a wasteful number, since it uses less digits than its factorization.

11771991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17011 (or 17008 counting only the distinct ones).

The product of its digits is 3969, while the sum is 36.

The square root of 11771991 is about 3431.0335177611. The cubic root of 11771991 is about 227.4835378339.

The spelling of 11771991 in words is "eleven million, seven hundred seventy-one thousand, nine hundred ninety-one".