12939721 has 4 divisors (see below), whose sum is σ = 12947200. Its totient is φ = 12932244.

The previous prime is 12939709. The next prime is 12939727. The reversal of 12939721 is 12793921.

It is a happy number.

12939721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 12793921 = 7 ⋅1827703.

It is a cyclic number.

It is not a de Polignac number, because 12939721 - 2¹⁵ = 12906953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12939727) 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, 340 + ... + 5098.

It is an arithmetic number, because the mean of its divisors is an integer number (3236800).

Almost surely, 2^12939721 is an apocalyptic number.

It is an amenable number.

12939721 is a deficient number, since it is larger than the sum of its proper divisors (7479).

12939721 is an equidigital number, since it uses as much as digits as its factorization.

12939721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7478.

The product of its digits is 6804, while the sum is 34.

The square root of 12939721 is about 3597.1823695776. The cubic root of 12939721 is about 234.7694796971.

The spelling of 12939721 in words is "twelve million, nine hundred thirty-nine thousand, seven hundred twenty-one".