1991773800 has 336 divisors, whose sum is σ = 7318728000. Its totient is φ = 502485120.

The previous prime is 1991773793. The next prime is 1991773813. The reversal of 1991773800 is 83771991.

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

It is an unprimeable number.

It is a polite number, since it can be written in 83 ways as a sum of consecutive naturals, for example, 2769841 + ... + 2770559.

Almost surely, 2^1991773800 is an apocalyptic number.

1991773800 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 1991773800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3659364000).

1991773800 is an abundant number, since it is smaller than the sum of its proper divisors (5326954200).

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

1991773800 is a wasteful number, since it uses less digits than its factorization.

1991773800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 772 (or 748 counting only the distinct ones).

The product of its (nonzero) digits is 95256, while the sum is 45.

The square root of 1991773800 is about 44629.2930708072. The cubic root of 1991773800 is about 1258.1912823971.

The spelling of 1991773800 in words is "one billion, nine hundred ninety-one million, seven hundred seventy-three thousand, eight hundred".