8221520 has 20 divisors (see below), whose sum is σ = 19115220. Its totient is φ = 3288576.

The previous prime is 8221513. The next prime is 8221537. The reversal of 8221520 is 251228.

It can be written as a sum of positive squares in 2 ways, for example, as 3794704 + 4426816 = 1948^2 + 2104^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a super-2 number, since 2×8221520² = 135186782220800, which contains 22 as substring.

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

It is a junction number, because it is equal to n+sod(n) for n = 8221492 and 8221501.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 51305 + ... + 51464.

It is an arithmetic number, because the mean of its divisors is an integer number (955761).

Almost surely, 2^8221520 is an apocalyptic number.

8221520 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

8221520 is an abundant number, since it is smaller than the sum of its proper divisors (10893700).

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

8221520 is a wasteful number, since it uses less digits than its factorization.

8221520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 102782 (or 102776 counting only the distinct ones).

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

The square root of 8221520 is about 2867.3193055535. The cubic root of 8221520 is about 201.8292187878.

Adding to 8221520 its reverse (251228), we get a palindrome (8472748).

The spelling of 8221520 in words is "eight million, two hundred twenty-one thousand, five hundred twenty".