7719721 has 2 divisors, whose sum is σ = 7719722. Its totient is φ = 7719720.

The previous prime is 7719689. The next prime is 7719727. The reversal of 7719721 is 1279177.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 3956121 + 3763600 = 1989^2 + 1940^2 .

It is an emirp because it is prime and its reverse (1279177) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 7719721 - 2⁵ = 7719689 is a prime.

It is not a weakly prime, because it can be changed into another prime (7719727) 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 as a sum of consecutive naturals, namely, 3859860 + 3859861.

It is an arithmetic number, because the mean of its divisors is an integer number (3859861).

Almost surely, 2^7719721 is an apocalyptic number.

It is an amenable number.

7719721 is a deficient number, since it is larger than the sum of its proper divisors (1).

7719721 is an equidigital number, since it uses as much as digits as its factorization.

7719721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6174, while the sum is 34.

The square root of 7719721 is about 2778.4385902877. The cubic root of 7719721 is about 197.6365215349.

The spelling of 7719721 in words is "seven million, seven hundred nineteen thousand, seven hundred twenty-one".