3991725 has 36 divisors (see below), whose sum is σ = 7258836. Its totient is φ = 2096640.

The previous prime is 3991723. The next prime is 3991727. The reversal of 3991725 is 5271993.

3991725 is a nontrivial binomial coefficient, being equal to C(2826, 2).

It is an interprime number because it is at equal distance from previous prime (3991723) and next prime (3991727).

It can be written as a sum of positive squares in 6 ways, for example, as 1179396 + 2812329 = 1086^2 + 1677^2 .

It is not a de Polignac number, because 3991725 - 2¹ = 3991723 is a prime.

3991725 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 3991725.

It is a congruent number.

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 (13) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 25347 + ... + 25503.

Almost surely, 2^3991725 is an apocalyptic number.

3991725 is the 2825-th triangular number and also the 1413-rd hexagonal number.

It is an amenable number.

3991725 is a deficient number, since it is larger than the sum of its proper divisors (3267111).

3991725 is a wasteful number, since it uses less digits than its factorization.

3991725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 286 (or 278 counting only the distinct ones).

The product of its digits is 17010, while the sum is 36.

The square root of 3991725 is about 1997.9301789602. The cubic root of 3991725 is about 158.6305650942.

The spelling of 3991725 in words is "three million, nine hundred ninety-one thousand, seven hundred twenty-five".