11961891 has 16 divisors (see below), whose sum is σ = 18333600. Its totient is φ = 7699104.

The previous prime is 11961871. The next prime is 11961899. The reversal of 11961891 is 19816911.

It is not a de Polignac number, because 11961891 - 2¹⁰ = 11960867 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (11961899) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6856 + ... + 8421.

It is an arithmetic number, because the mean of its divisors is an integer number (1145850).

Almost surely, 2^11961891 is an apocalyptic number.

11961891 is a deficient number, since it is larger than the sum of its proper divisors (6371709).

11961891 is a wasteful number, since it uses less digits than its factorization.

11961891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15315 (or 15309 counting only the distinct ones).

The product of its digits is 3888, while the sum is 36.

The square root of 11961891 is about 3458.5966807363. The cubic root of 11961891 is about 228.7002364203.

The spelling of 11961891 in words is "eleven million, nine hundred sixty-one thousand, eight hundred ninety-one".