12921921 has 12 divisors (see below), whose sum is σ = 19763172. Its totient is φ = 8107776.

The previous prime is 12921913. The next prime is 12921941. The reversal of 12921921 is 12912921.

It can be written as a sum of positive squares in 2 ways, for example, as 9235521 + 3686400 = 3039^2 + 1920^2 .

It is not a de Polignac number, because 12921921 - 2³ = 12921913 is a prime.

It is a zygodrome in base 3.

It is not an unprimeable number, because it can be changed into a prime (12921901) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 42076 + ... + 42381.

It is an arithmetic number, because the mean of its divisors is an integer number (1646931).

Almost surely, 2^12921921 is an apocalyptic number.

It is an amenable number.

12921921 is a deficient number, since it is larger than the sum of its proper divisors (6841251).

12921921 is a wasteful number, since it uses less digits than its factorization.

12921921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84480 (or 84477 counting only the distinct ones).

The product of its digits is 648, while the sum is 27.

The square root of 12921921 is about 3594.7073594383. The cubic root of 12921921 is about 234.6617799412.

The spelling of 12921921 in words is "twelve million, nine hundred twenty-one thousand, nine hundred twenty-one".