21022800 has 60 divisors (see below), whose sum is σ = 67346880. Its totient is φ = 5605760.

The previous prime is 21022783. The next prime is 21022801. The reversal of 21022800 is 822012.

It is a tau number, because it is divible by the number of its divisors (60).

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21022800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21022801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7560 + ... + 9959.

It is an arithmetic number, because the mean of its divisors is an integer number (1122448).

Almost surely, 2^21022800 is an apocalyptic number.

21022800 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21022800 is an abundant number, since it is smaller than the sum of its proper divisors (46324080).

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

21022800 is a wasteful number, since it uses less digits than its factorization.

21022800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17540 (or 17529 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 15.

The square root of 21022800 is about 4585.0627040423. The cubic root of 21022800 is about 275.9922283046.

Adding to 21022800 its reverse (822012), we get a palindrome (21844812).

The spelling of 21022800 in words is "twenty-one million, twenty-two thousand, eight hundred".