16181220 has 48 divisors (see below), whose sum is σ = 49428288. Its totient is φ = 3922560.

The previous prime is 16181203. The next prime is 16181227. The reversal of 16181220 is 2218161.

It is not an unprimeable number, because it can be changed into a prime (16181227) 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, 11599 + ... + 12918.

It is an arithmetic number, because the mean of its divisors is an integer number (1029756).

Almost surely, 2^16181220 is an apocalyptic number.

16181220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

16181220 is an abundant number, since it is smaller than the sum of its proper divisors (33247068).

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

16181220 is a wasteful number, since it uses less digits than its factorization.

16181220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24540 (or 24538 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 21.

The square root of 16181220 is about 4022.5887187233. The cubic root of 16181220 is about 252.9319860710.

Adding to 16181220 its reverse (2218161), we get a palindrome (18399381).

The spelling of 16181220 in words is "sixteen million, one hundred eighty-one thousand, two hundred twenty".