3999640 has 16 divisors (see below), whose sum is σ = 8999280. Its totient is φ = 1599840.

The previous prime is 3999637. The next prime is 3999647. The reversal of 3999640 is 469993.

3999640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (40), and also a Moran number because the ratio is a prime number: 99991 = 3999640 / (3 + 9 + 9 + 9 + 6 + 4 + 0).

It is a junction number, because it is equal to n+sod(n) for n = 3999593 and 3999602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3999647) 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, 49956 + ... + 50035.

It is an arithmetic number, because the mean of its divisors is an integer number (562455).

Almost surely, 2^3999640 is an apocalyptic number.

It is an amenable number.

3999640 is an abundant number, since it is smaller than the sum of its proper divisors (4999640).

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

3999640 is a wasteful number, since it uses less digits than its factorization.

3999640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 100002 (or 99998 counting only the distinct ones).

The product of its (nonzero) digits is 52488, while the sum is 40.

The square root of 3999640 is about 1999.9099979749. The cubic root of 3999640 is about 158.7353428508.

The spelling of 3999640 in words is "three million, nine hundred ninety-nine thousand, six hundred forty".