21800016 has 160 divisors (see below), whose sum is σ = 73209600. Its totient is φ = 6158592.

The previous prime is 21800003. The next prime is 21800017. The reversal of 21800016 is 61000812.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21800017) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 244900 + ... + 244988.

It is an arithmetic number, because the mean of its divisors is an integer number (457560).

Almost surely, 2^21800016 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21800016, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36604800).

21800016 is an abundant number, since it is smaller than the sum of its proper divisors (51409584).

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

21800016 is an frugal number, since it uses more digits than its factorization.

21800016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 125 (or 101 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 21800016 is about 4669.0487253829. The cubic root of 21800016 is about 279.3523124678.

Adding to 21800016 its reverse (61000812), we get a palindrome (82800828).

The spelling of 21800016 in words is "twenty-one million, eight hundred thousand, sixteen".