991078 has 16 divisors (see below), whose sum is σ = 1707840. Its totient is φ = 426600.

The previous prime is 991073. The next prime is 991079. The reversal of 991078 is 870199.

991078 = T₁₂₂ + T₁₂₃ + ... + T₁₉₇.

It is a plaindrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991073) by changing a digit.

991078 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 768 + ... + 1603.

It is an arithmetic number, because the mean of its divisors is an integer number (106740).

2⁹⁹¹⁰⁷⁸ is an apocalyptic number.

991078 is a deficient number, since it is larger than the sum of its proper divisors (716762).

991078 is a wasteful number, since it uses less digits than its factorization.

991078 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2403.

The product of its (nonzero) digits is 4536, while the sum is 34.

The square root of 991078 is about 995.5290051023. The cubic root of 991078 is about 99.7017111221.

The spelling of 991078 in words is "nine hundred ninety-one thousand, seventy-eight".