90991909091 has 4 divisors (see below), whose sum is σ = 91892819184. Its totient is φ = 90090999000.

The previous prime is 90991909061. The next prime is 90991909111. The reversal of 90991909091 is 19090919909.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19090919909 = 101 ⋅189019009.

It is a cyclic number.

It is not a de Polignac number, because 90991909091 - 2²² = 90987714787 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (90991909051) 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 3 ways as a sum of consecutive naturals, for example, 450454895 + ... + 450455096.

It is an arithmetic number, because the mean of its divisors is an integer number (22973204796).

Almost surely, 2^90991909091 is an apocalyptic number.

90991909091 is a deficient number, since it is larger than the sum of its proper divisors (900910093).

90991909091 is a wasteful number, since it uses less digits than its factorization.

90991909091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 900910092.

The product of its (nonzero) digits is 531441, while the sum is 56.

The spelling of 90991909091 in words is "ninety billion, nine hundred ninety-one million, nine hundred nine thousand, ninety-one".