11991951 has 6 divisors (see below), whose sum is σ = 17321720. Its totient is φ = 7994628.

The previous prime is 11991943. The next prime is 11991977. The reversal of 11991951 is 15919911.

11991951 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 11991951 - 2³ = 11991943 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11991911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 666211 + ... + 666228.

Almost surely, 2^11991951 is an apocalyptic number.

11991951 is a deficient number, since it is larger than the sum of its proper divisors (5329769).

11991951 is a wasteful number, since it uses less digits than its factorization.

11991951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1332445 (or 1332442 counting only the distinct ones).

The product of its digits is 3645, while the sum is 36.

The square root of 11991951 is about 3462.9396471784. The cubic root of 11991951 is about 228.8916492564.

The spelling of 11991951 in words is "eleven million, nine hundred ninety-one thousand, nine hundred fifty-one".