111667991 has 4 divisors (see below), whose sum is σ = 111922800. Its totient is φ = 111413184.

The previous prime is 111667987. The next prime is 111668047. The reversal of 111667991 is 199766111.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 199766111 = 107 ⋅1866973.

It is a cyclic number.

It is not a de Polignac number, because 111667991 - 2² = 111667987 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 (111667981) 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, 126746 + ... + 127623.

It is an arithmetic number, because the mean of its divisors is an integer number (27980700).

Almost surely, 2^111667991 is an apocalyptic number.

111667991 is a deficient number, since it is larger than the sum of its proper divisors (254809).

111667991 is an equidigital number, since it uses as much as digits as its factorization.

111667991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 254808.

The product of its digits is 20412, while the sum is 41.

The square root of 111667991 is about 10567.3076514314. The cubic root of 111667991 is about 481.5516784827.

The spelling of 111667991 in words is "one hundred eleven million, six hundred sixty-seven thousand, nine hundred ninety-one".