3935727721 has 4 divisors (see below), whose sum is σ = 4071442500. Its totient is φ = 3800012944.

The previous prime is 3935727707. The next prime is 3935727727. The reversal of 3935727721 is 1277275393.

It is a happy number.

3935727721 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: 1277275393 = 3469 ⋅368197.

It can be written as a sum of positive squares in 2 ways, for example, as 1976691600 + 1959036121 = 44460^2 + 44261^2 .

It is a cyclic number.

It is not a de Polignac number, because 3935727721 - 2⁹ = 3935727209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3935727727) 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, 67857346 + ... + 67857403.

It is an arithmetic number, because the mean of its divisors is an integer number (1017860625).

Almost surely, 2^3935727721 is an apocalyptic number.

It is an amenable number.

3935727721 is a deficient number, since it is larger than the sum of its proper divisors (135714779).

3935727721 is a wasteful number, since it uses less digits than its factorization.

3935727721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 135714778.

The product of its digits is 555660, while the sum is 46.

The square root of 3935727721 is about 62735.3785435300. The cubic root of 3935727721 is about 1578.8529463680.

The spelling of 3935727721 in words is "three billion, nine hundred thirty-five million, seven hundred twenty-seven thousand, seven hundred twenty-one".