12015721 has 4 divisors (see below), whose sum is σ = 12050500. Its totient is φ = 11980944.

The previous prime is 12015709. The next prime is 12015737. The reversal of 12015721 is 12751021.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12751021 = 59 ⋅216119.

It can be written as a sum of positive squares in 2 ways, for example, as 5198400 + 6817321 = 2280^2 + 2611^2 .

It is a cyclic number.

It is not a de Polignac number, because 12015721 - 2¹³ = 12007529 is a prime.

It is a super-2 number, since 2×12015721² = 288755102299682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12015701) 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, 16866 + ... + 17563.

It is an arithmetic number, because the mean of its divisors is an integer number (3012625).

Almost surely, 2^12015721 is an apocalyptic number.

It is an amenable number.

12015721 is a deficient number, since it is larger than the sum of its proper divisors (34779).

12015721 is an equidigital number, since it uses as much as digits as its factorization.

12015721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34778.

The product of its (nonzero) digits is 140, while the sum is 19.

The square root of 12015721 is about 3466.3700033320. The cubic root of 12015721 is about 229.0427829526.

Adding to 12015721 its reverse (12751021), we get a palindrome (24766742).

The spelling of 12015721 in words is "twelve million, fifteen thousand, seven hundred twenty-one".