991151 has 8 divisors (see below), whose sum is σ = 1199520. Its totient is φ = 799488.

The previous prime is 991147. The next prime is 991171. The reversal of 991151 is 151199.

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 991151 - 2² = 991147 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 991151.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991171) 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, 4046 + ... + 4283.

It is an arithmetic number, because the mean of its divisors is an integer number (149940).

2⁹⁹¹¹⁵¹ is an apocalyptic number.

991151 is a deficient number, since it is larger than the sum of its proper divisors (208369).

991151 is a wasteful number, since it uses less digits than its factorization.

991151 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8353.

The product of its digits is 405, while the sum is 26.

The square root of 991151 is about 995.5656683514. The cubic root of 991151 is about 99.7041589773.

The spelling of 991151 in words is "nine hundred ninety-one thousand, one hundred fifty-one".