21103220 has 24 divisors (see below), whose sum is σ = 44404584. Its totient is φ = 8424576.

The previous prime is 21103217. The next prime is 21103241. The reversal of 21103220 is 2230112.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 708964 + 20394256 = 842^2 + 4516^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16442 + ... + 17678.

It is an arithmetic number, because the mean of its divisors is an integer number (1850191).

Almost surely, 2^21103220 is an apocalyptic number.

21103220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21103220 is an abundant number, since it is smaller than the sum of its proper divisors (23301364).

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

21103220 is a wasteful number, since it uses less digits than its factorization.

21103220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2099 (or 2097 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 11.

The square root of 21103220 is about 4593.8241150484. The cubic root of 21103220 is about 276.3437046898.

Adding to 21103220 its reverse (2230112), we get a palindrome (23333332).

The spelling of 21103220 in words is "twenty-one million, one hundred three thousand, two hundred twenty".