7687721 has 4 divisors (see below), whose sum is σ = 7935744. Its totient is φ = 7439700.

The previous prime is 7687717. The next prime is 7687733. The reversal of 7687721 is 1277867.

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 7687721 - 2² = 7687717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7687711) 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, 123965 + ... + 124026.

It is an arithmetic number, because the mean of its divisors is an integer number (1983936).

Almost surely, 2^7687721 is an apocalyptic number.

It is an amenable number.

7687721 is a deficient number, since it is larger than the sum of its proper divisors (248023).

7687721 is a wasteful number, since it uses less digits than its factorization.

7687721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 248022.

The product of its digits is 32928, while the sum is 38.

The square root of 7687721 is about 2772.6739801138. The cubic root of 7687721 is about 197.3630605502.

The spelling of 7687721 in words is "seven million, six hundred eighty-seven thousand, seven hundred twenty-one".