7656721 has 8 divisors (see below), whose sum is σ = 7937024. Its totient is φ = 7378560.

The previous prime is 7656713. The next prime is 7656731. The reversal of 7656721 is 1276567.

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 7656721 - 2³ = 7656713 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7656731) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11041 + ... + 11713.

It is an arithmetic number, because the mean of its divisors is an integer number (992128).

It is a Poulet number, since it divides 2^7656720-1.

Almost surely, 2^7656721 is an apocalyptic number.

It is an amenable number.

7656721 is a deficient number, since it is larger than the sum of its proper divisors (280303).

7656721 is a wasteful number, since it uses less digits than its factorization.

7656721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1071.

The product of its digits is 17640, while the sum is 34.

The square root of 7656721 is about 2767.0780617829. The cubic root of 7656721 is about 197.0974206157.

The spelling of 7656721 in words is "seven million, six hundred fifty-six thousand, seven hundred twenty-one".