11891921 has 4 divisors (see below), whose sum is σ = 11945472. Its totient is φ = 11838372.

The previous prime is 11891917. The next prime is 11891933. The reversal of 11891921 is 12919811.

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: 12919811 = 67 ⋅192833.

It is a cyclic number.

It is not a de Polignac number, because 11891921 - 2² = 11891917 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11891021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26441 + ... + 26886.

It is an arithmetic number, because the mean of its divisors is an integer number (2986368).

Almost surely, 2^11891921 is an apocalyptic number.

It is an amenable number.

11891921 is a deficient number, since it is larger than the sum of its proper divisors (53551).

11891921 is an equidigital number, since it uses as much as digits as its factorization.

11891921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53550.

The product of its digits is 1296, while the sum is 32.

The square root of 11891921 is about 3448.4664707664. The cubic root of 11891921 is about 228.2534436742.

The spelling of 11891921 in words is "eleven million, eight hundred ninety-one thousand, nine hundred twenty-one".