8521220 has 12 divisors (see below), whose sum is σ = 17894604. Its totient is φ = 3408480.

The previous prime is 8521213. The next prime is 8521223. The reversal of 8521220 is 221258.

It can be written as a sum of positive squares in 2 ways, for example, as 1844164 + 6677056 = 1358^2 + 2584^2 .

It is a super-2 number, since 2×8521220² = 145222380576800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (20), and also a Moran number because the ratio is a prime number: 426061 = 8521220 / (8 + 5 + 2 + 1 + 2 + 2 + 0).

It is a junction number, because it is equal to n+sod(n) for n = 8521192 and 8521201.

It is not an unprimeable number, because it can be changed into a prime (8521223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 213011 + ... + 213050.

It is an arithmetic number, because the mean of its divisors is an integer number (1491217).

Almost surely, 2^8521220 is an apocalyptic number.

It is an amenable number.

8521220 is an abundant number, since it is smaller than the sum of its proper divisors (9373384).

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

8521220 is a wasteful number, since it uses less digits than its factorization.

8521220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 426070 (or 426068 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 20.

The square root of 8521220 is about 2919.1128789411. The cubic root of 8521220 is about 204.2524428325.

Adding to 8521220 its reverse (221258), we get a palindrome (8742478).

The spelling of 8521220 in words is "eight million, five hundred twenty-one thousand, two hundred twenty".