1991261200 has 60 divisors (see below), whose sum is σ = 4895303248. Its totient is φ = 777974400.

The previous prime is 1991261197. The next prime is 1991261201. The reversal of 1991261200 is 21621991.

It is not an unprimeable number, because it can be changed into a prime (1991261201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 40686 + ... + 75085.

Almost surely, 2^1991261200 is an apocalyptic number.

1991261200 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1991261200 is an abundant number, since it is smaller than the sum of its proper divisors (2904042048).

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

1991261200 is a wasteful number, since it uses less digits than its factorization.

1991261200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 115832 (or 115821 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 31.

The square root of 1991261200 is about 44623.5498363812. The cubic root of 1991261200 is about 1258.0833377120.

The spelling of 1991261200 in words is "one billion, nine hundred ninety-one million, two hundred sixty-one thousand, two hundred".