509856221 has 18 divisors (see below), whose sum is σ = 614575710. Its totient is φ = 421245552.

The previous prime is 509856209. The next prime is 509856223. The reversal of 509856221 is 122658905.

It can be written as a sum of positive squares in only one way, i.e., 439531225 + 70324996 = 20965^2 + 8386^2 .

It is not a de Polignac number, because 509856221 - 2¹⁸ = 509594077 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (509856223) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 850880 + ... + 851478.

It is an arithmetic number, because the mean of its divisors is an integer number (34143095).

Almost surely, 2^509856221 is an apocalyptic number.

It is an amenable number.

509856221 is a deficient number, since it is larger than the sum of its proper divisors (104719489).

509856221 is an frugal number, since it uses more digits than its factorization.

509856221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1241 (or 635 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 38.

The square root of 509856221 is about 22579.9960363150. The cubic root of 509856221 is about 798.8818864431.

The spelling of 509856221 in words is "five hundred nine million, eight hundred fifty-six thousand, two hundred twenty-one".