7728661 has 4 divisors (see below), whose sum is σ = 7753824. Its totient is φ = 7703500.

The previous prime is 7728647. The next prime is 7728673. The reversal of 7728661 is 1668277.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 7728661 - 2⁷ = 7728533 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 7728661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7728601) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12115 + ... + 12736.

It is an arithmetic number, because the mean of its divisors is an integer number (1938456).

Almost surely, 2^7728661 is an apocalyptic number.

It is an amenable number.

7728661 is a deficient number, since it is larger than the sum of its proper divisors (25163).

7728661 is a wasteful number, since it uses less digits than its factorization.

7728661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25162.

The product of its digits is 28224, while the sum is 37.

The square root of 7728661 is about 2780.0469420497. The cubic root of 7728661 is about 197.7127846056.

The spelling of 7728661 in words is "seven million, seven hundred twenty-eight thousand, six hundred sixty-one".