991018 has 16 divisors (see below), whose sum is σ = 1724544. Its totient is φ = 418320.

The previous prime is 991009. The next prime is 991027. The reversal of 991018 is 810199.

It is an interprime number because it is at equal distance from previous prime (991009) and next prime (991027).

It is an Ulam number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 496 + ... + 1492.

It is an arithmetic number, because the mean of its divisors is an integer number (107784).

2⁹⁹¹⁰¹⁸ is an apocalyptic number.

991018 is a deficient number, since it is larger than the sum of its proper divisors (733526).

991018 is a wasteful number, since it uses less digits than its factorization.

991018 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1077.

The product of its (nonzero) digits is 648, while the sum is 28.

The square root of 991018 is about 995.4988699140. The cubic root of 991018 is about 99.6996990964.

The spelling of 991018 in words is "nine hundred ninety-one thousand, eighteen".