520985991 has 4 divisors (see below), whose sum is σ = 694647992. Its totient is φ = 347323992.

The previous prime is 520985981. The next prime is 520985999. The reversal of 520985991 is 199589025.

It is a happy number.

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

It is not a de Polignac number, because 520985991 - 2¹¹ = 520983943 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 520985991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (520985999) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 86830996 + ... + 86831001.

It is an arithmetic number, because the mean of its divisors is an integer number (173661998).

Almost surely, 2^520985991 is an apocalyptic number.

520985991 is a deficient number, since it is larger than the sum of its proper divisors (173662001).

520985991 is a wasteful number, since it uses less digits than its factorization.

520985991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 173662000.

The product of its (nonzero) digits is 291600, while the sum is 48.

The square root of 520985991 is about 22825.1175462472. The cubic root of 520985991 is about 804.6530871494.

The spelling of 520985991 in words is "five hundred twenty million, nine hundred eighty-five thousand, nine hundred ninety-one".