7087721 has 4 divisors (see below), whose sum is σ = 7097412. Its totient is φ = 7078032.

The previous prime is 7087697. The next prime is 7087723. The reversal of 7087721 is 1277807.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2088025 + 4999696 = 1445^2 + 2236^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7087721 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (7087723) 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 3 ways as a sum of consecutive naturals, for example, 3650 + ... + 5243.

It is an arithmetic number, because the mean of its divisors is an integer number (1774353).

Almost surely, 2^7087721 is an apocalyptic number.

It is an amenable number.

7087721 is a deficient number, since it is larger than the sum of its proper divisors (9691).

7087721 is an equidigital number, since it uses as much as digits as its factorization.

7087721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9690.

The product of its (nonzero) digits is 5488, while the sum is 32.

The square root of 7087721 is about 2662.2774085358. The cubic root of 7087721 is about 192.0888712564.

The spelling of 7087721 in words is "seven million, eighty-seven thousand, seven hundred twenty-one".