3991961280 has 224 divisors, whose sum is σ = 12932688384. Its totient is φ = 1043103744.

The previous prime is 3991961261. The next prime is 3991961321. The reversal of 3991961280 is 821691993.

It is a super-2 number, since 2×3991961280² = 31871509722038476800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 15178429 + ... + 15178691.

It is an arithmetic number, because the mean of its divisors is an integer number (57735216).

Almost surely, 2^3991961280 is an apocalyptic number.

3991961280 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 3991961280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (6466344192).

3991961280 is an abundant number, since it is smaller than the sum of its proper divisors (8940727104).

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

3991961280 is a wasteful number, since it uses less digits than its factorization.

3991961280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 543 (or 533 counting only the distinct ones).

The product of its (nonzero) digits is 209952, while the sum is 48.

The square root of 3991961280 is about 63181.9695799363. The cubic root of 3991961280 is about 1586.3369494323.

The spelling of 3991961280 in words is "three billion, nine hundred ninety-one million, nine hundred sixty-one thousand, two hundred eighty".