545991 has 4 divisors (see below), whose sum is σ = 727992. Its totient is φ = 363992.

The previous prime is 545959. The next prime is 546001. The reversal of 545991 is 199545.

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 545991 - 2⁵ = 545959 is a prime.

It is a D-number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (545911) 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, 90996 + ... + 91001.

It is an arithmetic number, because the mean of its divisors is an integer number (181998).

2⁵⁴⁵⁹⁹¹ is an apocalyptic number.

545991 is a deficient number, since it is larger than the sum of its proper divisors (182001).

545991 is a wasteful number, since it uses less digits than its factorization.

545991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 182000.

The product of its digits is 8100, while the sum is 33.

The square root of 545991 is about 738.9120380668. The cubic root of 545991 is about 81.7325711706.

The spelling of 545991 in words is "five hundred forty-five thousand, nine hundred ninety-one".