521400420 has 72 divisors (see below), whose sum is σ = 1596993216. Its totient is φ = 137685312.

The previous prime is 521400401. The next prime is 521400431. The reversal of 521400420 is 24004125.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 521400393 and 521400402.

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, 4479 + ... + 32601.

Almost surely, 2^521400420 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 521400420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (798496608).

521400420 is an abundant number, since it is smaller than the sum of its proper divisors (1075592796).

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

521400420 is a wasteful number, since it uses less digits than its factorization.

521400420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28241 (or 28236 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 18.

The square root of 521400420 is about 22834.1940956978. The cubic root of 521400420 is about 804.8663898721.

Adding to 521400420 its reverse (24004125), we get a palindrome (545404545).

The spelling of 521400420 in words is "five hundred twenty-one million, four hundred thousand, four hundred twenty".