105217991 has 4 divisors (see below), whose sum is σ = 110755800. Its totient is φ = 99680184.

The previous prime is 105217979. The next prime is 105218011. The reversal of 105217991 is 199712501.

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 105217991 - 2²² = 101023687 is a prime.

It is a super-2 number, since 2×105217991² = 22141651260152162, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (105217901) 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 3 ways as a sum of consecutive naturals, for example, 2768876 + ... + 2768913.

It is an arithmetic number, because the mean of its divisors is an integer number (27688950).

Almost surely, 2^105217991 is an apocalyptic number.

105217991 is a deficient number, since it is larger than the sum of its proper divisors (5537809).

105217991 is an equidigital number, since it uses as much as digits as its factorization.

105217991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5537808.

The product of its (nonzero) digits is 5670, while the sum is 35.

The square root of 105217991 is about 10257.5821225082. The cubic root of 105217991 is about 472.0956532536.

The spelling of 105217991 in words is "one hundred five million, two hundred seventeen thousand, nine hundred ninety-one".