291128991 has 8 divisors (see below), whose sum is σ = 388415664. Its totient is φ = 193964160.

The previous prime is 291128977. The next prime is 291129011. The reversal of 291128991 is 199821192.

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

It is not a de Polignac number, because 291128991 - 2¹³ = 291120799 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (291128911) 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, 24730 + ... + 34551.

It is an arithmetic number, because the mean of its divisors is an integer number (48551958).

Almost surely, 2^291128991 is an apocalyptic number.

291128991 is a deficient number, since it is larger than the sum of its proper divisors (97286673).

291128991 is a wasteful number, since it uses less digits than its factorization.

291128991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60921.

The product of its digits is 23328, while the sum is 42.

The square root of 291128991 is about 17062.5024835163. The cubic root of 291128991 is about 662.7684378411.

The spelling of 291128991 in words is "two hundred ninety-one million, one hundred twenty-eight thousand, nine hundred ninety-one".