1991261760 has 112 divisors (see below), whose sum is σ = 6476585472. Its totient is φ = 518041600.

The previous prime is 1991261747. The next prime is 1991261773. The reversal of 1991261760 is 671621991.

It is an interprime number because it is at equal distance from previous prime (1991261747) and next prime (1991261773).

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, 14065 + ... + 64655.

It is an arithmetic number, because the mean of its divisors is an integer number (57826656).

Almost surely, 2^1991261760 is an apocalyptic number.

1991261760 is a gapful number since it is divisible by the number (10) 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 1991261760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3238292736).

1991261760 is an abundant number, since it is smaller than the sum of its proper divisors (4485323712).

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

1991261760 is a wasteful number, since it uses less digits than its factorization.

1991261760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50652 (or 50642 counting only the distinct ones).

The product of its (nonzero) digits is 40824, while the sum is 42.

The square root of 1991261760 is about 44623.5561110945. The cubic root of 1991261760 is about 1258.0834556484.

The spelling of 1991261760 in words is "one billion, nine hundred ninety-one million, two hundred sixty-one thousand, seven hundred sixty".