3999440 has 20 divisors (see below), whose sum is σ = 9298884. Its totient is φ = 1599744.

The previous prime is 3999439. The next prime is 3999449. The reversal of 3999440 is 449993.

3999440 is nontrivially palindromic in base 15.

It can be written as a sum of positive squares in 2 ways, for example, as 2050624 + 1948816 = 1432^2 + 1396^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a junction number, because it is equal to n+sod(n) for n = 3999394 and 3999403.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3999449) 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, 24917 + ... + 25076.

Almost surely, 2^3999440 is an apocalyptic number.

It is an amenable number.

3999440 is an abundant number, since it is smaller than the sum of its proper divisors (5299444).

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

3999440 is a wasteful number, since it uses less digits than its factorization.

3999440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50006 (or 50000 counting only the distinct ones).

The product of its (nonzero) digits is 34992, while the sum is 38.

The square root of 3999440 is about 1999.8599950997. The cubic root of 3999440 is about 158.7326969795.

The spelling of 3999440 in words is "three million, nine hundred ninety-nine thousand, four hundred forty".