520644909 has 4 divisors (see below), whose sum is σ = 694193216. Its totient is φ = 347096604.

The previous prime is 520644893. The next prime is 520644923. The reversal of 520644909 is 909446025.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 520644909 - 2⁴ = 520644893 is a prime.

It is a super-2 number, since 2×520644909² = 542142242535236562, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (520644809) 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, 86774149 + ... + 86774154.

It is an arithmetic number, because the mean of its divisors is an integer number (173548304).

Almost surely, 2^520644909 is an apocalyptic number.

It is an amenable number.

520644909 is a deficient number, since it is larger than the sum of its proper divisors (173548307).

520644909 is a wasteful number, since it uses less digits than its factorization.

520644909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173548306.

The product of its (nonzero) digits is 77760, while the sum is 39.

The square root of 520644909 is about 22817.6446856375. The cubic root of 520644909 is about 804.4774505653.

The spelling of 520644909 in words is "five hundred twenty million, six hundred forty-four thousand, nine hundred nine".