90909191 has 4 divisors (see below), whose sum is σ = 91809384. Its totient is φ = 90009000.

The previous prime is 90909157. The next prime is 90909193. The reversal of 90909191 is 19190909.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 90909191 - 2⁶ = 90909127 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (90909193) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 449945 + ... + 450146.

It is an arithmetic number, because the mean of its divisors is an integer number (22952346).

Almost surely, 2^90909191 is an apocalyptic number.

90909191 is a deficient number, since it is larger than the sum of its proper divisors (900193).

90909191 is a wasteful number, since it uses less digits than its factorization.

90909191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 900192.

The product of its (nonzero) digits is 6561, while the sum is 38.

The square root of 90909191 is about 9534.6311412660. The cubic root of 90909191 is about 449.6444780420.

It can be divided in two parts, 9090 and 9191, that added together give a palindrome (18281).

The spelling of 90909191 in words is "ninety million, nine hundred nine thousand, one hundred ninety-one".