521202420 has 72 divisors (see below), whose sum is σ = 1596689640. Its totient is φ = 137606400.

The previous prime is 521202403. The next prime is 521202427. The reversal of 521202420 is 24202125.

It can be written as a sum of positive squares in 4 ways, for example, as 258373476 + 262828944 = 16074^2 + 16212^2 .

It is a super-2 number, since 2×521202420² = 543303925227712800, which contains 22 as substring.

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 = 521202393 and 521202402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (521202427) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3846 + ... + 32514.

It is an arithmetic number, because the mean of its divisors is an integer number (22176245).

Almost surely, 2^521202420 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 521202420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (798344820).

521202420 is an abundant number, since it is smaller than the sum of its proper divisors (1075487220).

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

521202420 is a wasteful number, since it uses less digits than its factorization.

521202420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28785 (or 28780 counting only the distinct ones).

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

The square root of 521202420 is about 22829.8580810306. The cubic root of 521202420 is about 804.7644952335.

Adding to 521202420 its reverse (24202125), we get a palindrome (545404545).

The spelling of 521202420 in words is "five hundred twenty-one million, two hundred two thousand, four hundred twenty".