521440400 has 120 divisors (see below), whose sum is σ = 1360199400. Its totient is φ = 190955520.

The previous prime is 521440397. The next prime is 521440417. The reversal of 521440400 is 4044125.

It can be written as a sum of positive squares in 12 ways, for example, as 386043904 + 135396496 = 19648^2 + 11636^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 774464 + ... + 775136.

It is an arithmetic number, because the mean of its divisors is an integer number (11334995).

Almost surely, 2^521440400 is an apocalyptic number.

521440400 is a gapful number since it is divisible by the number (50) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 521440400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (680099700).

521440400 is an abundant number, since it is smaller than the sum of its proper divisors (838759000).

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

521440400 is a wasteful number, since it uses less digits than its factorization.

521440400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 853 (or 842 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 20.

The square root of 521440400 is about 22835.0695203671. The cubic root of 521440400 is about 804.8869612248.

Adding to 521440400 its reverse (4044125), we get a palindrome (525484525).

The spelling of 521440400 in words is "five hundred twenty-one million, four hundred forty thousand, four hundred".