12009891 has 4 divisors (see below), whose sum is σ = 16013192. Its totient is φ = 8006592.

The previous prime is 12009869. The next prime is 12009901. The reversal of 12009891 is 19890021.

12009891 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 a semiprime because it is the product of two primes.

It is not a de Polignac number, because 12009891 - 2⁵ = 12009859 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12009821) 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, 2001646 + ... + 2001651.

It is an arithmetic number, because the mean of its divisors is an integer number (4003298).

Almost surely, 2^12009891 is an apocalyptic number.

12009891 is a deficient number, since it is larger than the sum of its proper divisors (4003301).

12009891 is an equidigital number, since it uses as much as digits as its factorization.

12009891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4003300.

The product of its (nonzero) digits is 1296, while the sum is 30.

The square root of 12009891 is about 3465.5289639534. The cubic root of 12009891 is about 229.0057332839.

The spelling of 12009891 in words is "twelve million, nine thousand, eight hundred ninety-one".