12457721 has 2 divisors, whose sum is σ = 12457722. Its totient is φ = 12457720.

The previous prime is 12457717. The next prime is 12457729. The reversal of 12457721 is 12775421.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7639696 + 4818025 = 2764^2 + 2195^2 .

It is an emirp because it is prime and its reverse (12775421) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 12457721 - 2² = 12457717 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (12457729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6228860 + 6228861.

It is an arithmetic number, because the mean of its divisors is an integer number (6228861).

Almost surely, 2^12457721 is an apocalyptic number.

It is an amenable number.

12457721 is a deficient number, since it is larger than the sum of its proper divisors (1).

12457721 is an equidigital number, since it uses as much as digits as its factorization.

12457721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3920, while the sum is 29.

The square root of 12457721 is about 3529.5496879914. The cubic root of 12457721 is about 231.8174904783.

The spelling of 12457721 in words is "twelve million, four hundred fifty-seven thousand, seven hundred twenty-one".