3991336320 has 128 divisors (see below), whose sum is σ = 12897116640. Its totient is φ = 1049739264.

The previous prime is 3991336319. The next prime is 3991336331. The reversal of 3991336320 is 236331993.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (128).

It is a super-2 number, since 2×3991336320² = 31861531238702284800, which contains 22 as substring.

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, 125922 + ... + 154398.

Almost surely, 2^3991336320 is an apocalyptic number.

3991336320 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 3991336320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (6448558320).

3991336320 is an abundant number, since it is smaller than the sum of its proper divisors (8905780320).

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

3991336320 is a wasteful number, since it uses less digits than its factorization.

3991336320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28572 (or 28560 counting only the distinct ones).

The product of its (nonzero) digits is 78732, while the sum is 39.

The square root of 3991336320 is about 63177.0236715849. The cubic root of 3991336320 is about 1586.2541623167.

The spelling of 3991336320 in words is "three billion, nine hundred ninety-one million, three hundred thirty-six thousand, three hundred twenty".