16665220 has 48 divisors (see below), whose sum is σ = 41122368. Its totient is φ = 5592960.

The previous prime is 16665193. The next prime is 16665221. The reversal of 16665220 is 2256661.

16665220 = 474² + 475² + ... + 538².

16665220 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (16665221) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 54 + ... + 5773.

It is an arithmetic number, because the mean of its divisors is an integer number (856716).

Almost surely, 2^16665220 is an apocalyptic number.

16665220 is a gapful number since it is divisible by the number (10) 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 16665220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (20561184).

16665220 is an abundant number, since it is smaller than the sum of its proper divisors (24457148).

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

16665220 is a wasteful number, since it uses less digits than its factorization.

16665220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5860 (or 5858 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 16665220 is about 4082.3057210356. The cubic root of 16665220 is about 255.4290866219.

It can be divided in two parts, 1666 and 5220, that added together give a palindrome (6886).

The spelling of 16665220 in words is "sixteen million, six hundred sixty-five thousand, two hundred twenty".