12021172891 has 24 divisors (see below), whose sum is σ = 15078752640. Its totient is φ = 9499093632.

The previous prime is 12021172859. The next prime is 12021172921. The reversal of 12021172891 is 19827112021.

It is not a de Polignac number, because 12021172891 - 2⁵ = 12021172859 is a prime.

It is not an unprimeable number, because it can be changed into a prime (12021172811) 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, 503670 + ... + 526996.

It is an arithmetic number, because the mean of its divisors is an integer number (628281360).

Almost surely, 2^12021172891 is an apocalyptic number.

12021172891 is a deficient number, since it is larger than the sum of its proper divisors (3057579749).

12021172891 is a wasteful number, since it uses less digits than its factorization.

12021172891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24163 (or 24156 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 34.

The spelling of 12021172891 in words is "twelve billion, twenty-one million, one hundred seventy-two thousand, eight hundred ninety-one".