21041620 has 36 divisors (see below), whose sum is σ = 45318420. Its totient is φ = 8206464.

The previous prime is 21041609. The next prime is 21041621. The reversal of 21041620 is 2614012.

It can be written as a sum of positive squares in 2 ways, for example, as 5391684 + 15649936 = 2322^2 + 3956^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21041594 and 21041603.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21041621) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 36696 + ... + 37264.

It is an arithmetic number, because the mean of its divisors is an integer number (1258845).

Almost surely, 2^21041620 is an apocalyptic number.

21041620 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 21041620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22659210).

21041620 is an abundant number, since it is smaller than the sum of its proper divisors (24276800).

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

21041620 is a wasteful number, since it uses less digits than its factorization.

21041620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 664 (or 619 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 16.

The square root of 21041620 is about 4587.1145614645. The cubic root of 21041620 is about 276.0745615259.

Adding to 21041620 its reverse (2614012), we get a palindrome (23655632).

The spelling of 21041620 in words is "twenty-one million, forty-one thousand, six hundred twenty".