3909712721 has 4 divisors (see below), whose sum is σ = 3910203444. Its totient is φ = 3909222000.

The previous prime is 3909712663. The next prime is 3909712733. The reversal of 3909712721 is 1272179093.

3909712721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1272179093 = 1279 ⋅994667.

It can be written as a sum of positive squares in 2 ways, for example, as 3017854225 + 891858496 = 54935^2 + 29864^2 .

It is a cyclic number.

It is not a de Polignac number, because 3909712721 - 2⁶ = 3909712657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3909711721) 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, 233210 + ... + 249411.

It is an arithmetic number, because the mean of its divisors is an integer number (977550861).

Almost surely, 2^3909712721 is an apocalyptic number.

It is an amenable number.

3909712721 is a deficient number, since it is larger than the sum of its proper divisors (490723).

3909712721 is an equidigital number, since it uses as much as digits as its factorization.

3909712721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 490722.

The product of its (nonzero) digits is 47628, while the sum is 41.

The square root of 3909712721 is about 62527.6956316159. The cubic root of 3909712721 is about 1575.3665354706.

The spelling of 3909712721 in words is "three billion, nine hundred nine million, seven hundred twelve thousand, seven hundred twenty-one".