991005311 has 4 divisors (see below), whose sum is σ = 991800000. Its totient is φ = 990210624.

The previous prime is 991005307. The next prime is 991005317. The reversal of 991005311 is 113500199.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 113500199 = 61 ⋅1860659.

It is a cyclic number.

It is not a de Polignac number, because 991005311 - 2² = 991005307 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 (991005317) 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, 395471 + ... + 397968.

It is an arithmetic number, because the mean of its divisors is an integer number (247950000).

Almost surely, 2^991005311 is an apocalyptic number.

991005311 is a deficient number, since it is larger than the sum of its proper divisors (794689).

991005311 is a wasteful number, since it uses less digits than its factorization.

991005311 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 794688.

The product of its (nonzero) digits is 1215, while the sum is 29.

The square root of 991005311 is about 31480.2368320189. The cubic root of 991005311 is about 996.9927357607.

The spelling of 991005311 in words is "nine hundred ninety-one million, five thousand, three hundred eleven".