521872221 has 16 divisors (see below), whose sum is σ = 788795840. Its totient is φ = 304248960.

The previous prime is 521872189. The next prime is 521872249. The reversal of 521872221 is 122278125.

It is not a de Polignac number, because 521872221 - 2⁵ = 521872189 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (521872621) 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 15 ways as a sum of consecutive naturals, for example, 351400 + ... + 352881.

It is an arithmetic number, because the mean of its divisors is an integer number (49299740).

Almost surely, 2^521872221 is an apocalyptic number.

It is an amenable number.

521872221 is a deficient number, since it is larger than the sum of its proper divisors (266923619).

521872221 is a wasteful number, since it uses less digits than its factorization.

521872221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 704316.

The product of its digits is 4480, while the sum is 30.

The square root of 521872221 is about 22844.5227789945. The cubic root of 521872221 is about 805.1090838892.

The spelling of 521872221 in words is "five hundred twenty-one million, eight hundred seventy-two thousand, two hundred twenty-one".