991820500 has 48 divisors (see below), whose sum is σ = 2363070528. Its totient is φ = 360660000.

The previous prime is 991820471. The next prime is 991820509. The reversal of 991820500 is 5028199.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991820509) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 84666 + ... + 95665.

It is an arithmetic number, because the mean of its divisors is an integer number (49230636).

Almost surely, 2^991820500 is an apocalyptic number.

It is an amenable number.

991820500 is an abundant number, since it is smaller than the sum of its proper divisors (1371250028).

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

991820500 is a wasteful number, since it uses less digits than its factorization.

991820500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 180361 (or 180349 counting only the distinct ones).

The product of its (nonzero) digits is 6480, while the sum is 34.

The square root of 991820500 is about 31493.1818017805. The cubic root of 991820500 is about 997.2660322320.

Adding to 991820500 its reverse (5028199), we get a palindrome (996848699).

The spelling of 991820500 in words is "nine hundred ninety-one million, eight hundred twenty thousand, five hundred".