1991871330 has 16 divisors (see below), whose sum is σ = 4780491264. Its totient is φ = 531165680.

The previous prime is 1991871313. The next prime is 1991871337. The reversal of 1991871330 is 331781991.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1991871337) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33197826 + ... + 33197885.

It is an arithmetic number, because the mean of its divisors is an integer number (298780704).

Almost surely, 2^1991871330 is an apocalyptic number.

1991871330 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1991871330 is an abundant number, since it is smaller than the sum of its proper divisors (2788619934).

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

1991871330 is a wasteful number, since it uses less digits than its factorization.

1991871330 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66395721.

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

The square root of 1991871330 is about 44630.3857254225. The cubic root of 1991871330 is about 1258.2118184293.

The spelling of 1991871330 in words is "one billion, nine hundred ninety-one million, eight hundred seventy-one thousand, three hundred thirty".