3991806720 has 648 divisors, whose sum is σ = 16152055920. Its totient is φ = 902430720.

The previous prime is 3991806713. The next prime is 3991806727. The reversal of 3991806720 is 276081993.

3991806720 is a `hidden beast` number, since 399 + 180 + 67 + 20 = 666.

It is an interprime number because it is at equal distance from previous prime (3991806713) and next prime (3991806727).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (3991806727) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 36622026 + ... + 36622134.

Almost surely, 2^3991806720 is an apocalyptic number.

3991806720 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 3991806720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (8076027960).

3991806720 is an abundant number, since it is smaller than the sum of its proper divisors (12160249200).

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

3991806720 is a wasteful number, since it uses less digits than its factorization.

3991806720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 181 (or 147 counting only the distinct ones).

The product of its (nonzero) digits is 163296, while the sum is 45.

The square root of 3991806720 is about 63180.7464343371. The cubic root of 3991806720 is about 1586.3164760036.

The spelling of 3991806720 in words is "three billion, nine hundred ninety-one million, eight hundred six thousand, seven hundred twenty".