12171921 has 8 divisors (see below), whose sum is σ = 16378560. Its totient is φ = 8039952.

The previous prime is 12171917. The next prime is 12171923. The reversal of 12171921 is 12917121.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 12171921 - 2² = 12171917 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 12171891 and 12171900.

It is not an unprimeable number, because it can be changed into a prime (12171923) 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 7 ways as a sum of consecutive naturals, for example, 18285 + ... + 18938.

It is an arithmetic number, because the mean of its divisors is an integer number (2047320).

Almost surely, 2^12171921 is an apocalyptic number.

It is an amenable number.

12171921 is a deficient number, since it is larger than the sum of its proper divisors (4206639).

12171921 is a wasteful number, since it uses less digits than its factorization.

12171921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37335.

The product of its digits is 252, while the sum is 24.

The square root of 12171921 is about 3488.8280267161. The cubic root of 12171921 is about 230.0310040120.

The spelling of 12171921 in words is "twelve million, one hundred seventy-one thousand, nine hundred twenty-one".