991861200 has 600 divisors, whose sum is σ = 4085649216. Its totient is φ = 229996800.

The previous prime is 991861153. The next prime is 991861207. The reversal of 991861200 is 2168199.

It is a tau number, because it is divible by the number of its divisors (600).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991861207) by changing a digit.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 43124389 + ... + 43124411.

Almost surely, 2^991861200 is an apocalyptic number.

991861200 is a gapful number since it is divisible by the number (90) 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 991861200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2042824608).

991861200 is an abundant number, since it is smaller than the sum of its proper divisors (3093788016).

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

991861200 is a wasteful number, since it uses less digits than its factorization.

991861200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86 (or 44 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 36.

The square root of 991861200 is about 31493.8279667620. The cubic root of 991861200 is about 997.2796731991.

The spelling of 991861200 in words is "nine hundred ninety-one million, eight hundred sixty-one thousand, two hundred".