91289991 has 8 divisors (see below), whose sum is σ = 131083120. Its totient is φ = 56178432.

The previous prime is 91289981. The next prime is 91289993. The reversal of 91289991 is 19998219.

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

It is not a de Polignac number, because 91289991 - 2⁵ = 91289959 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 91289991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91289993) 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, 1170346 + ... + 1170423.

It is an arithmetic number, because the mean of its divisors is an integer number (16385390).

Almost surely, 2^91289991 is an apocalyptic number.

91289991 is a deficient number, since it is larger than the sum of its proper divisors (39793129).

91289991 is a wasteful number, since it uses less digits than its factorization.

91289991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2340785.

The product of its digits is 104976, while the sum is 48.

The square root of 91289991 is about 9554.5795825876. The cubic root of 91289991 is about 450.2714263744.

The spelling of 91289991 in words is "ninety-one million, two hundred eighty-nine thousand, nine hundred ninety-one".