21253650 has 72 divisors (see below), whose sum is σ = 57985872. Its totient is φ = 5148000.

The previous prime is 21253649. The next prime is 21253657. The reversal of 21253650 is 5635212.

It is a self number, because there is not a number n which added to its sum of digits gives 21253650.

It is not an unprimeable number, because it can be changed into a prime (21253657) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 17565 + ... + 18735.

Almost surely, 2^21253650 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21253650, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28992936).

21253650 is an abundant number, since it is smaller than the sum of its proper divisors (36732222).

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

21253650 is a wasteful number, since it uses less digits than its factorization.

21253650 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1208 (or 1192 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 24.

The square root of 21253650 is about 4610.1681097331. The cubic root of 21253650 is about 276.9987705593.

Adding to 21253650 its reverse (5635212), we get a palindrome (26888862).

It can be divided in two parts, 2125 and 3650, that added together give a palindrome (5775).

The spelling of 21253650 in words is "twenty-one million, two hundred fifty-three thousand, six hundred fifty".