21850020 has 96 divisors (see below), whose sum is σ = 69632640. Its totient is φ = 5685120.

The previous prime is 21849979. The next prime is 21850027. The reversal of 21850020 is 2005812.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21849975 and 21850002.

It is not an unprimeable number, because it can be changed into a prime (21850027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 22750 + ... + 23690.

It is an arithmetic number, because the mean of its divisors is an integer number (725340).

Almost surely, 2^21850020 is an apocalyptic number.

21850020 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 21850020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34816320).

21850020 is an abundant number, since it is smaller than the sum of its proper divisors (47782620).

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

21850020 is a wasteful number, since it uses less digits than its factorization.

21850020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1002 (or 994 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

The square root of 21850020 is about 4674.4004963204. The cubic root of 21850020 is about 279.5657384016.

Adding to 21850020 its reverse (2005812), we get a palindrome (23855832).

The spelling of 21850020 in words is "twenty-one million, eight hundred fifty thousand, twenty".