991803600 has 270 divisors, whose sum is σ = 3547387350. Its totient is φ = 256596480.

The previous prime is 991803581. The next prime is 991803607. The reversal of 991803600 is 6308199.

It can be written as a sum of positive squares in 3 ways, for example, as 1065024 + 990738576 = 1032^2 + 31476^2 .

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 (991803607) by changing a digit.

It is a polite number, since it can be written in 53 ways as a sum of consecutive naturals, for example, 6656326 + ... + 6656474.

Almost surely, 2^991803600 is an apocalyptic number.

991803600 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 991803600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1773693675).

991803600 is an abundant number, since it is smaller than the sum of its proper divisors (2555583750).

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

991803600 is a wasteful number, since it uses less digits than its factorization.

991803600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 259 (or 202 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 36.

The square root of 991803600 is about 31492.9134885930. The cubic root of 991803600 is about 997.2603679370.

The spelling of 991803600 in words is "nine hundred ninety-one million, eight hundred three thousand, six hundred".