7720561 has 2 divisors, whose sum is σ = 7720562. Its totient is φ = 7720560.

The previous prime is 7720529. The next prime is 7720589. The reversal of 7720561 is 1650277.

It is an a-pointer prime, because the next prime (7720589) can be obtained adding 7720561 to its sum of digits (28).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6630625 + 1089936 = 2575^2 + 1044^2 .

It is a cyclic number.

It is not a de Polignac number, because 7720561 - 2⁵ = 7720529 is a prime.

It is not a weakly prime, because it can be changed into another prime (7720861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3860280 + 3860281.

It is an arithmetic number, because the mean of its divisors is an integer number (3860281).

Almost surely, 2^7720561 is an apocalyptic number.

It is an amenable number.

7720561 is a deficient number, since it is larger than the sum of its proper divisors (1).

7720561 is an equidigital number, since it uses as much as digits as its factorization.

7720561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2940, while the sum is 28.

The square root of 7720561 is about 2778.5897502150. The cubic root of 7720561 is about 197.6436896980.

It can be divided in two parts, 7720 and 561, that added together give a square (8281 = 91²).

The spelling of 7720561 in words is "seven million, seven hundred twenty thousand, five hundred sixty-one".