3991720 has 16 divisors (see below), whose sum is σ = 8981460. Its totient is φ = 1596672.

The previous prime is 3991717. The next prime is 3991723. The reversal of 3991720 is 271993.

3991720 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (3991717) and next prime (3991723).

It can be written as a sum of positive squares in 2 ways, for example, as 3944196 + 47524 = 1986^2 + 218^2 .

It is not an unprimeable number, because it can be changed into a prime (3991723) 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, 49857 + ... + 49936.

Almost surely, 2^3991720 is an apocalyptic number.

It is an amenable number.

3991720 is an abundant number, since it is smaller than the sum of its proper divisors (4989740).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

3991720 is a wasteful number, since it uses less digits than its factorization.

3991720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99804 (or 99800 counting only the distinct ones).

The product of its (nonzero) digits is 3402, while the sum is 31.

The square root of 3991720 is about 1997.9289276648. The cubic root of 3991720 is about 158.6304988610.

The spelling of 3991720 in words is "three million, nine hundred ninety-one thousand, seven hundred twenty".