7775721 has 12 divisors (see below), whose sum is σ = 11265540. Its totient is φ = 5168160.

The previous prime is 7775717. The next prime is 7775737. The reversal of 7775721 is 1275777.

It is a happy number.

7775721 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 3515625 + 4260096 = 1875^2 + 2064^2 .

It is not a de Polignac number, because 7775721 - 2² = 7775717 is a prime.

It is not an unprimeable number, because it can be changed into a prime (7775701) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2391 + ... + 4611.

It is an arithmetic number, because the mean of its divisors is an integer number (938795).

Almost surely, 2^7775721 is an apocalyptic number.

It is an amenable number.

7775721 is a deficient number, since it is larger than the sum of its proper divisors (3489819).

7775721 is a wasteful number, since it uses less digits than its factorization.

7775721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2616 (or 2613 counting only the distinct ones).

The product of its digits is 24010, while the sum is 36.

The square root of 7775721 is about 2788.4979827857. The cubic root of 7775721 is about 198.1132654668.

The spelling of 7775721 in words is "seven million, seven hundred seventy-five thousand, seven hundred twenty-one".