191616991 has 8 divisors (see below), whose sum is σ = 194126544. Its totient is φ = 189120960.

The previous prime is 191616989. The next prime is 191617051. The reversal of 191616991 is 199616191.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 191616991 - 2¹ = 191616989 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 (191616941) 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, 26881 + ... + 33253.

It is an arithmetic number, because the mean of its divisors is an integer number (24265818).

Almost surely, 2^191616991 is an apocalyptic number.

191616991 is a deficient number, since it is larger than the sum of its proper divisors (2509553).

191616991 is a wasteful number, since it uses less digits than its factorization.

191616991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6761.

The product of its digits is 26244, while the sum is 43.

The square root of 191616991 is about 13842.5789143497. The cubic root of 191616991 is about 576.5159654244.

The spelling of 191616991 in words is "one hundred ninety-one million, six hundred sixteen thousand, nine hundred ninety-one".