16651220 has 48 divisors (see below), whose sum is σ = 38102400. Its totient is φ = 6088320.

The previous prime is 16651199. The next prime is 16651237. The reversal of 16651220 is 2215661.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10265 + ... + 11775.

It is an arithmetic number, because the mean of its divisors is an integer number (793800).

Almost surely, 2^16651220 is an apocalyptic number.

16651220 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 16651220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (19051200).

16651220 is an abundant number, since it is smaller than the sum of its proper divisors (21451180).

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

16651220 is a wasteful number, since it uses less digits than its factorization.

16651220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1568 (or 1566 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 16651220 is about 4080.5906435221. The cubic root of 16651220 is about 255.3575402307.

Adding to 16651220 its reverse (2215661), we get a palindrome (18866881).

The spelling of 16651220 in words is "sixteen million, six hundred fifty-one thousand, two hundred twenty".