191919091 has 16 divisors (see below), whose sum is σ = 236988864. Its totient is φ = 151346304.

The previous prime is 191919083. The next prime is 191919097. The reversal of 191919091 is 190919191.

It is a cyclic number.

It is not a de Polignac number, because 191919091 - 2³ = 191919083 is a prime.

It is a zygodrome in base 9.

It is not an unprimeable number, because it can be changed into a prime (191919097) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25521 + ... + 32173.

It is an arithmetic number, because the mean of its divisors is an integer number (14811804).

Almost surely, 2^191919091 is an apocalyptic number.

191919091 is a deficient number, since it is larger than the sum of its proper divisors (45069773).

191919091 is a wasteful number, since it uses less digits than its factorization.

191919091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6990.

The product of its (nonzero) digits is 6561, while the sum is 40.

The square root of 191919091 is about 13853.4866008525. The cubic root of 191919091 is about 576.8187813413.

It can be divided in two parts, 19191 and 9091, that added together give a palindrome (28282).

The spelling of 191919091 in words is "one hundred ninety-one million, nine hundred nineteen thousand, ninety-one".