99891991920 has 240 divisors, whose sum is σ = 371844200448. Its totient is φ = 22095843840.

The previous prime is 99891991879. The next prime is 99891991933. The reversal of 99891991920 is 2919919899.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (240).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 227557 + ... + 501563.

Almost surely, 2^99891991920 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 99891991920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (185922100224).

99891991920 is an abundant number, since it is smaller than the sum of its proper divisors (271952208528).

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

99891991920 is a wasteful number, since it uses less digits than its factorization.

99891991920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 274068 (or 274055 counting only the distinct ones).

The product of its (nonzero) digits is 8503056, while the sum is 66.

The spelling of 99891991920 in words is "ninety-nine billion, eight hundred ninety-one million, nine hundred ninety-one thousand, nine hundred twenty".