990991081091 has 8 divisors (see below), whose sum is σ = 1081504002864. Its totient is φ = 900548629920.

The previous prime is 990991081081. The next prime is 990991081111. The reversal of 990991081091 is 190180199099.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 990991081091 - 2¹⁰ = 990991080067 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (990991081001) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17588240 + ... + 17644493.

It is an arithmetic number, because the mean of its divisors is an integer number (135188000358).

Almost surely, 2^990991081091 is an apocalyptic number.

990991081091 is a deficient number, since it is larger than the sum of its proper divisors (90512921773).

990991081091 is a wasteful number, since it uses less digits than its factorization.

990991081091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35235301.

The product of its (nonzero) digits is 472392, while the sum is 56.

It can be divided in two parts, 99099108 and 1091, that added together give a palindrome (99100199).

The spelling of 990991081091 in words is "nine hundred ninety billion, nine hundred ninety-one million, eighty-one thousand, ninety-one".