3991680 has 320 divisors, whose sum is σ = 17772480. Its totient is φ = 829440.

The previous prime is 3991679. The next prime is 3991681. The reversal of 3991680 is 861993.

It is an interprime number because it is at equal distance from previous prime (3991679) and next prime (3991681).

It is a tau number, because it is divible by the number of its divisors (320).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (3991681) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 362875 + ... + 362885.

It is an arithmetic number, because the mean of its divisors is an integer number (55539).

Almost surely, 2^3991680 is an apocalyptic number.

3991680 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 3991680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (8886240).

3991680 is an abundant number, since it is smaller than the sum of its proper divisors (13780800).

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

3991680 is a wasteful number, since it uses less digits than its factorization.

3991680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49 (or 28 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 36.

The square root of 3991680 is about 1997.9189172737. The cubic root of 3991680 is about 158.6299689941.

It can be divided in two parts, 39 and 91680, that added together give a palindrome (91719).

The spelling of 3991680 in words is "three million, nine hundred ninety-one thousand, six hundred eighty".