Adding to 21020000 its reverse (2012), we get a palindrome (21022012).
It is a congruent number.
It is an unprimeable number.
Almost surely, 221020000 is an apocalyptic number.
21020000 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 21020000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25880778).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
21020000 is an equidigital number, since it uses as much as digits as its factorization.
21020000 is an evil number, because the sum of its binary digits is even.
The square root of 21020000 is about 4584.7573545391. The cubic root of 21020000 is about 275.9799747426.
The spelling of 21020000 in words is "twenty-one million, twenty thousand".