21200220 has 36 divisors (see below), whose sum is σ = 64307880. Its totient is φ = 5653344.

The previous prime is 21200209. The next prime is 21200233. The reversal of 21200220 is 2200212.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 58710 + ... + 59069.

It is an arithmetic number, because the mean of its divisors is an integer number (1786330).

Almost surely, 2^21200220 is an apocalyptic number.

21200220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21200220 is an abundant number, since it is smaller than the sum of its proper divisors (43107660).

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

21200220 is a wasteful number, since it uses less digits than its factorization.

21200220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117794 (or 117789 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 9.

The square root of 21200220 is about 4604.3696636999. The cubic root of 21200220 is about 276.7664580905.

Adding to 21200220 its reverse (2200212), we get a palindrome (23400432).

The spelling of 21200220 in words is "twenty-one million, two hundred thousand, two hundred twenty".