12667721 has 4 divisors (see below), whose sum is σ = 13819344. Its totient is φ = 11516100.

The previous prime is 12667667. The next prime is 12667777. The reversal of 12667721 is 12776621.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 12667721 - 2¹⁰ = 12666697 is a prime.

It is not an unprimeable number, because it can be changed into a prime (12667021) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 575795 + ... + 575816.

It is an arithmetic number, because the mean of its divisors is an integer number (3454836).

Almost surely, 2^12667721 is an apocalyptic number.

12667721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

12667721 is a deficient number, since it is larger than the sum of its proper divisors (1151623).

12667721 is a wasteful number, since it uses less digits than its factorization.

12667721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1151622.

The product of its digits is 7056, while the sum is 32.

The square root of 12667721 is about 3559.1742019744. The cubic root of 12667721 is about 233.1128227389.

Subtracting 12667721 from its reverse (12776621), we obtain a square (108900 = 330²).

The spelling of 12667721 in words is "twelve million, six hundred sixty-seven thousand, seven hundred twenty-one".