7720521 has 16 divisors (see below), whose sum is σ = 10659264. Its totient is φ = 4967424.

The previous prime is 7720507. The next prime is 7720529. The reversal of 7720521 is 1250277.

7720521 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 7720521 - 2⁷ = 7720393 is a prime.

It is a super-2 number, since 2×7720521² = 119212889022882, which contains 22 as substring.

It is an Ulam number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 7720491 and 7720500.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7720529) 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 in 15 ways as a sum of consecutive naturals, for example, 12205 + ... + 12821.

It is an arithmetic number, because the mean of its divisors is an integer number (666204).

Almost surely, 2^7720521 is an apocalyptic number.

It is an amenable number.

7720521 is a deficient number, since it is larger than the sum of its proper divisors (2938743).

7720521 is a wasteful number, since it uses less digits than its factorization.

7720521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 760.

The product of its (nonzero) digits is 980, while the sum is 24.

The square root of 7720521 is about 2778.5825523097. The cubic root of 7720521 is about 197.6433483687.

Adding to 7720521 its reverse (1250277), we get a palindrome (8970798).

The spelling of 7720521 in words is "seven million, seven hundred twenty thousand, five hundred twenty-one".