520005721 has 4 divisors (see below), whose sum is σ = 521207092. Its totient is φ = 518804352.

The previous prime is 520005719. The next prime is 520005727. The reversal of 520005721 is 127500025.

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

It can be written as a sum of positive squares in 2 ways, for example, as 35521600 + 484484121 = 5960^2 + 22011^2 .

It is a cyclic number.

It is not a de Polignac number, because 520005721 - 2¹ = 520005719 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 520005692 and 520005701.

It is not an unprimeable number, because it can be changed into a prime (520005727) 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, 600036 + ... + 600901.

It is an arithmetic number, because the mean of its divisors is an integer number (130301773).

Almost surely, 2^520005721 is an apocalyptic number.

It is an amenable number.

520005721 is a deficient number, since it is larger than the sum of its proper divisors (1201371).

520005721 is a wasteful number, since it uses less digits than its factorization.

520005721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1201370.

The product of its (nonzero) digits is 700, while the sum is 22.

The square root of 520005721 is about 22803.6339428609. The cubic root of 520005721 is about 804.1481007547.

Adding to 520005721 its reverse (127500025), we get a palindrome (647505746).

The spelling of 520005721 in words is "five hundred twenty million, five thousand, seven hundred twenty-one".