991900000 has 288 divisors, whose sum is σ = 3031680960. Its totient is φ = 311040000.

The previous prime is 991899977. The next prime is 991900009. The reversal of 991900000 is 9199.

991900000 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×991900000² = 1967731220000000000, which contains 22 as substring.

It is a hoax number, since the sum of its digits (28) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991900009) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 9099946 + ... + 9100054.

It is an arithmetic number, because the mean of its divisors is an integer number (10526670).

Almost surely, 2^991900000 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 991900000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1515840480).

991900000 is an abundant number, since it is smaller than the sum of its proper divisors (2039780960).

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

991900000 is a wasteful number, since it uses less digits than its factorization.

991900000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 164 (or 136 counting only the distinct ones).

The product of its (nonzero) digits is 729, while the sum is 28.

The square root of 991900000 is about 31494.4439544501. The cubic root of 991900000 is about 997.2926770168.

Adding to 991900000 its reverse (9199), we get a palindrome (991909199).

The spelling of 991900000 in words is "nine hundred ninety-one million, nine hundred thousand".