7957721 has 2 divisors, whose sum is σ = 7957722. Its totient is φ = 7957720.

The previous prime is 7957699. The next prime is 7957727. The reversal of 7957721 is 1277597.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 4494400 + 3463321 = 2120^2 + 1861^2 .

It is an emirp because it is prime and its reverse (1277597) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7957721 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (7957727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3978860 + 3978861.

It is an arithmetic number, because the mean of its divisors is an integer number (3978861).

Almost surely, 2^7957721 is an apocalyptic number.

It is an amenable number.

7957721 is a deficient number, since it is larger than the sum of its proper divisors (1).

7957721 is an equidigital number, since it uses as much as digits as its factorization.

7957721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 30870, while the sum is 38.

The square root of 7957721 is about 2820.9432819538. The cubic root of 7957721 is about 199.6470525067.

The spelling of 7957721 in words is "seven million, nine hundred fifty-seven thousand, seven hundred twenty-one".