21230220 has 96 divisors (see below), whose sum is σ = 68302080. Its totient is φ = 4872960.

The previous prime is 21230213. The next prime is 21230227. The reversal of 21230220 is 2203212.

It is an interprime number because it is at equal distance from previous prime (21230213) and next prime (21230227).

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21230196 and 21230205.

It is not an unprimeable number, because it can be changed into a prime (21230227) 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, 11694 + ... + 13386.

It is an arithmetic number, because the mean of its divisors is an integer number (711480).

Almost surely, 2^21230220 is an apocalyptic number.

21230220 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 21230220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34151040).

21230220 is an abundant number, since it is smaller than the sum of its proper divisors (47071860).

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

21230220 is a wasteful number, since it uses less digits than its factorization.

21230220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1735 (or 1733 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 12.

The square root of 21230220 is about 4607.6262869291. The cubic root of 21230220 is about 276.8969454212.

Adding to 21230220 its reverse (2203212), we get a palindrome (23433432).

The spelling of 21230220 in words is "twenty-one million, two hundred thirty thousand, two hundred twenty".