7720661 has 8 divisors (see below), whose sum is σ = 8409240. Its totient is φ = 7045632.

The previous prime is 7720649. The next prime is 7720667. The reversal of 7720661 is 1660277.

It can be written as a sum of positive squares in 4 ways, for example, as 532900 + 7187761 = 730^2 + 2681^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 7720661 - 2⁶ = 7720597 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7720667) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2180 + ... + 4493.

It is an arithmetic number, because the mean of its divisors is an integer number (1051155).

Almost surely, 2^7720661 is an apocalyptic number.

It is an amenable number.

7720661 is a deficient number, since it is larger than the sum of its proper divisors (688579).

7720661 is a wasteful number, since it uses less digits than its factorization.

7720661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6775.

The product of its (nonzero) digits is 3528, while the sum is 29.

The square root of 7720661 is about 2778.6077448967. The cubic root of 7720661 is about 197.6445430161.

The spelling of 7720661 in words is "seven million, seven hundred twenty thousand, six hundred sixty-one".