3991240 has 64 divisors (see below), whose sum is σ = 10056960. Its totient is φ = 1413120.

The previous prime is 3991237. The next prime is 3991261. The reversal of 3991240 is 421993.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 3991199 and 3991208.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20584 + ... + 20776.

It is an arithmetic number, because the mean of its divisors is an integer number (157140).

Almost surely, 2^3991240 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 3991240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (5028480).

3991240 is an abundant number, since it is smaller than the sum of its proper divisors (6065720).

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

3991240 is a wasteful number, since it uses less digits than its factorization.

3991240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 262 (or 258 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 28.

The square root of 3991240 is about 1997.8087996603. The cubic root of 3991240 is about 158.6241402244.

The spelling of 3991240 in words is "three million, nine hundred ninety-one thousand, two hundred forty".