991885109742 has 160 divisors (see below), whose sum is σ = 2477362231872. Its totient is φ = 295013892096.

The previous prime is 991885109717. The next prime is 991885109749. The reversal of 991885109742 is 247901588199.

It is a Smith number, since the sum of its digits (63) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 991885109742.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991885109749) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 7088358 + ... + 7226934.

Almost surely, 2^991885109742 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 991885109742, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1238681115936).

991885109742 is an abundant number, since it is smaller than the sum of its proper divisors (1485477122130).

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

991885109742 is a wasteful number, since it uses less digits than its factorization.

991885109742 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 138744 (or 138735 counting only the distinct ones).

The product of its (nonzero) digits is 13063680, while the sum is 63.

The spelling of 991885109742 in words is "nine hundred ninety-one billion, eight hundred eighty-five million, one hundred nine thousand, seven hundred forty-two".