991550 has 24 divisors (see below), whose sum is σ = 2108496. Its totient is φ = 339840.

The previous prime is 991547. The next prime is 991567. The reversal of 991550 is 55199.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1067 + ... + 1766.

It is an arithmetic number, because the mean of its divisors is an integer number (87854).

2⁹⁹¹⁵⁵⁰ is an apocalyptic number.

991550 is an abundant number, since it is smaller than the sum of its proper divisors (1116946).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

991550 is a wasteful number, since it uses less digits than its factorization.

991550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2852 (or 2847 counting only the distinct ones).

The product of its (nonzero) digits is 2025, while the sum is 29.

The square root of 991550 is about 995.7660367777. The cubic root of 991550 is about 99.7175362267.

The spelling of 991550 in words is "nine hundred ninety-one thousand, five hundred fifty".