991573 has 8 divisors (see below), whose sum is σ = 1092960. Its totient is φ = 892080.

The previous prime is 991567. The next prime is 991579. The reversal of 991573 is 375199.

991573 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (991567) and next prime (991579).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 991573 - 2⁵ = 991541 is a prime.

It is a super-3 number, since 3×991573³ = 2924794333647748551, which contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991579) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 786 + ... + 1612.

It is an arithmetic number, because the mean of its divisors is an integer number (136620).

2⁹⁹¹⁵⁷³ is an apocalyptic number.

It is an amenable number.

991573 is a deficient number, since it is larger than the sum of its proper divisors (101387).

991573 is a wasteful number, since it uses less digits than its factorization.

991573 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 947.

The product of its digits is 8505, while the sum is 34.

The square root of 991573 is about 995.7775856084. Note that the first 3 decimals coincide. The cubic root of 991573 is about 99.7183072370.

The spelling of 991573 in words is "nine hundred ninety-one thousand, five hundred seventy-three".