3109721 has 4 divisors (see below), whose sum is σ = 3113700. Its totient is φ = 3105744.

The previous prime is 3109709. The next prime is 3109747. The reversal of 3109721 is 1279013.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 2131600 + 978121 = 1460^2 + 989^2 .

It is a cyclic number.

It is not a de Polignac number, because 3109721 - 2¹⁰ = 3108697 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 (3109751) 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, 386 + ... + 2523.

It is an arithmetic number, because the mean of its divisors is an integer number (778425).

Almost surely, 2^3109721 is an apocalyptic number.

It is an amenable number.

3109721 is a deficient number, since it is larger than the sum of its proper divisors (3979).

3109721 is a wasteful number, since it uses less digits than its factorization.

3109721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3978.

The product of its (nonzero) digits is 378, while the sum is 23.

The square root of 3109721 is about 1763.4401038879. The cubic root of 3109721 is about 145.9622251682.

The spelling of 3109721 in words is "three million, one hundred nine thousand, seven hundred twenty-one".