1991116400 has 240 divisors, whose sum is σ = 6199603200. Its totient is φ = 596782080.

The previous prime is 1991116397. The next prime is 1991116411. The reversal of 1991116400 is 46111991.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 690161 + ... + 693039.

It is an arithmetic number, because the mean of its divisors is an integer number (25831680).

Almost surely, 2^1991116400 is an apocalyptic number.

1991116400 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 1991116400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3099801600).

1991116400 is an abundant number, since it is smaller than the sum of its proper divisors (4208486800).

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

1991116400 is a wasteful number, since it uses less digits than its factorization.

1991116400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2936 (or 2925 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 32.

The square root of 1991116400 is about 44621.9273451966. The cubic root of 1991116400 is about 1258.0528419834.

The spelling of 1991116400 in words is "one billion, nine hundred ninety-one million, one hundred sixteen thousand, four hundred".