12445721 has 4 divisors (see below), whose sum is σ = 12481332. Its totient is φ = 12410112.

The previous prime is 12445711. The next prime is 12445723. The reversal of 12445721 is 12754421.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12754421 = 311 ⋅41011.

It can be written as a sum of positive squares in 2 ways, for example, as 1974025 + 10471696 = 1405^2 + 3236^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-12445721 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (12445723) 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, 17276 + ... + 17981.

It is an arithmetic number, because the mean of its divisors is an integer number (3120333).

Almost surely, 2^12445721 is an apocalyptic number.

It is an amenable number.

12445721 is a deficient number, since it is larger than the sum of its proper divisors (35611).

12445721 is an equidigital number, since it uses as much as digits as its factorization.

12445721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35610.

The product of its digits is 2240, while the sum is 26.

The square root of 12445721 is about 3527.8493448559. The cubic root of 12445721 is about 231.7430332116.

The spelling of 12445721 in words is "twelve million, four hundred forty-five thousand, seven hundred twenty-one".