• 220 can be written using four 4's:

220 has 12 divisors (see below), whose sum is σ = 504. Its totient is φ = 80.

The previous prime is 211. The next prime is 223. The reversal of 220 is 22.

220 = T_{1} + T_{2} + ... +
T_{10}.

220 is an esthetic number in base 16, because in such base its adjacent digits differ by 1.

220 is a nontrivial binomial coefficient, being equal to C(12, 3).

220 is a Gilda number.

It is a Harshad number since it is a multiple of its sum of digits (4).

It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.

Together with 284 it forms an amicable pair .

It is a plaindrome in base 8, base 13 and base 14.

It is a nialpdrome in base 7, base 10, base 15 and base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (223) by changing a digit.

It is the 10-th tetrahedral number.

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, 15 + ... + 25.

It is an arithmetic number, because the mean of its divisors is an integer number (42).

2^{220} is an apocalyptic number.

220 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 220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (252).

220 is an abundant number, since it is smaller than the sum of its proper divisors (284).

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

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

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

The sum of its prime factors is 20 (or 18 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 4.

The square root of 220 is about 14.8323969742. The cubic root of 220 is about 6.0368107368.

Adding to 220 its reverse (22), we get a palindrome (242).

It can be divided in two parts, 2 and 20, that added together give a palindrome (22).

The spelling of 220 in words is "two hundred twenty", and thus it is an aban number and an iban number.

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