550991 has 4 divisors (see below), whose sum is σ = 629712. Its totient is φ = 472272.

The previous prime is 550973. The next prime is 550993. The reversal of 550991 is 199055.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 550991 - 2¹⁴ = 534607 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 (550993) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 39350 + ... + 39363.

It is an arithmetic number, because the mean of its divisors is an integer number (157428).

2⁵⁵⁰⁹⁹¹ is an apocalyptic number.

550991 is a deficient number, since it is larger than the sum of its proper divisors (78721).

550991 is an equidigital number, since it uses as much as digits as its factorization.

550991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78720.

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

The square root of 550991 is about 742.2876800810. The cubic root of 550991 is about 81.9813064665.

The spelling of 550991 in words is "five hundred fifty thousand, nine hundred ninety-one".