521323440 has 160 divisors (see below), whose sum is σ = 1774386432. Its totient is φ = 125568000.

The previous prime is 521323421. The next prime is 521323447. The reversal of 521323440 is 44323125.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 521323440.

It is not an unprimeable number, because it can be changed into a prime (521323447) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 477295 + ... + 478385.

Almost surely, 2^521323440 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 521323440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (887193216).

521323440 is an abundant number, since it is smaller than the sum of its proper divisors (1253062992).

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

521323440 is a wasteful number, since it uses less digits than its factorization.

521323440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1299 (or 1293 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 24.

The square root of 521323440 is about 22832.5084035898. The cubic root of 521323440 is about 804.8267775372.

Adding to 521323440 its reverse (44323125), we get a palindrome (565646565).

The spelling of 521323440 in words is "five hundred twenty-one million, three hundred twenty-three thousand, four hundred forty".