521255440 has 120 divisors (see below), whose sum is σ = 1289839320. Its totient is φ = 195858432.

The previous prime is 521255393. The next prime is 521255447. The reversal of 521255440 is 44552125.

It can be written as a sum of positive squares in 4 ways, for example, as 4875264 + 516380176 = 2208^2 + 22724^2 .

It is a junction number, because it is equal to n+sod(n) for n = 521255399 and 521255408.

It is not an unprimeable number, because it can be changed into a prime (521255447) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4612824 + ... + 4612936.

It is an arithmetic number, because the mean of its divisors is an integer number (10748661).

Almost surely, 2^521255440 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 521255440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (644919660).

521255440 is an abundant number, since it is smaller than the sum of its proper divisors (768583880).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

521255440 is a wasteful number, since it uses less digits than its factorization.

521255440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 281 (or 252 counting only the distinct ones).

The product of its (nonzero) digits is 8000, while the sum is 28.

The square root of 521255440 is about 22831.0192501342. The cubic root of 521255440 is about 804.7917828830.

The spelling of 521255440 in words is "five hundred twenty-one million, two hundred fifty-five thousand, four hundred forty".