221520 has 80 divisors (see below), whose sum is σ = 749952. Its totient is φ = 53760.

The previous prime is 221509. The next prime is 221537. The reversal of 221520 is 25122.

221520 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (80).

It is a super-2 number, since 2×221520² = 98142220800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 221496 and 221505.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3085 + ... + 3155.

2²²¹⁵²⁰ is an apocalyptic number.

221520 is a gapful number since it is divisible by the number (20) 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 221520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (374976).

221520 is an abundant number, since it is smaller than the sum of its proper divisors (528432).

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

221520 is a wasteful number, since it uses less digits than its factorization.

221520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 100 (or 94 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 12.

The square root of 221520 is about 470.6591123095. The cubic root of 221520 is about 60.5068179826.

Adding to 221520 its reverse (25122), we get a palindrome (246642).

It can be divided in two parts, 221 and 520, that added together give a triangular number (741 = T₃₈).

The spelling of 221520 in words is "two hundred twenty-one thousand, five hundred twenty".