991825920 has 156 divisors (see below), whose sum is σ = 3438549036. Its totient is φ = 264437760.

The previous prime is 991825871. The next prime is 991825921. The reversal of 991825920 is 29528199.

It can be written as a sum of positive squares in 2 ways, for example, as 339738624 + 652087296 = 18432^2 + 25536^2 .

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

It is not an unprimeable number, because it can be changed into a prime (991825921) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 181630 + ... + 187010.

It is an arithmetic number, because the mean of its divisors is an integer number (22041981).

Almost surely, 2^991825920 is an apocalyptic number.

991825920 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 991825920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1719274518).

991825920 is an abundant number, since it is smaller than the sum of its proper divisors (2446723116).

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

991825920 is a wasteful number, since it uses less digits than its factorization.

991825920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5416 (or 5391 counting only the distinct ones).

The product of its (nonzero) digits is 116640, while the sum is 45.

The square root of 991825920 is about 31493.2678520347. The cubic root of 991825920 is about 997.2678488148.

The spelling of 991825920 in words is "nine hundred ninety-one million, eight hundred twenty-five thousand, nine hundred twenty".