21016800 has 288 divisors, whose sum is σ = 87494400. Its totient is φ = 4769280.

The previous prime is 21016799. The next prime is 21016813. The reversal of 21016800 is 861012.

It is a tau number, because it is divible by the number of its divisors (288).

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 151131 + ... + 151269.

It is an arithmetic number, because the mean of its divisors is an integer number (303800).

Almost surely, 2^21016800 is an apocalyptic number.

21016800 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 21016800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43747200).

21016800 is an abundant number, since it is smaller than the sum of its proper divisors (66477600).

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

21016800 is a wasteful number, since it uses less digits than its factorization.

21016800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 175 (or 156 counting only the distinct ones).

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

The square root of 21016800 is about 4584.4083587743. The cubic root of 21016800 is about 275.9659693392.

Adding to 21016800 its reverse (861012), we get a palindrome (21877812).

The spelling of 21016800 in words is "twenty-one million, sixteen thousand, eight hundred".