3999681 has 12 divisors (see below), whose sum is σ = 6602752. Its totient is φ = 2285496.

The previous prime is 3999661. The next prime is 3999683. The reversal of 3999681 is 1869993.

3999681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 3999681 - 2¹⁵ = 3966913 is a prime.

It is a super-2 number, since 2×3999681² = 31994896203522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3999683) 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 11 ways as a sum of consecutive naturals, for example, 31681 + ... + 31806.

Almost surely, 2^3999681 is an apocalyptic number.

It is an amenable number.

3999681 is a deficient number, since it is larger than the sum of its proper divisors (2603071).

3999681 is a wasteful number, since it uses less digits than its factorization.

3999681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63500 (or 63497 counting only the distinct ones).

The product of its digits is 104976, while the sum is 45.

The square root of 3999681 is about 1999.9202484099. The cubic root of 3999681 is about 158.7358852435.

The spelling of 3999681 in words is "three million, nine hundred ninety-nine thousand, six hundred eighty-one".