525991 has 4 divisors (see below), whose sum is σ = 527472. Its totient is φ = 524512.

The previous prime is 525983. The next prime is 526027. The reversal of 525991 is 199525.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 525991 - 2³ = 525983 is a prime.

It is a Duffinian number.

525991 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (525961) 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, 150 + ... + 1036.

It is an arithmetic number, because the mean of its divisors is an integer number (131868).

2⁵²⁵⁹⁹¹ is an apocalyptic number.

525991 is a deficient number, since it is larger than the sum of its proper divisors (1481).

525991 is an equidigital number, since it uses as much as digits as its factorization.

525991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1480.

The product of its digits is 4050, while the sum is 31.

The square root of 525991 is about 725.2523698686. The cubic root of 525991 is about 80.7221593742.

The spelling of 525991 in words is "five hundred twenty-five thousand, nine hundred ninety-one".