21850840 has 64 divisors (see below), whose sum is σ = 54704160. Its totient is φ = 7787520.

The previous prime is 21850819. The next prime is 21850849. The reversal of 21850840 is 4805812.

It is a junction number, because it is equal to n+sod(n) for n = 21850799 and 21850808.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21850849) 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 15 ways as a sum of consecutive naturals, for example, 22852 + ... + 23788.

Almost surely, 2^21850840 is an apocalyptic number.

21850840 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 21850840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27352080).

21850840 is an abundant number, since it is smaller than the sum of its proper divisors (32853320).

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

21850840 is a wasteful number, since it uses less digits than its factorization.

21850840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1012 (or 1008 counting only the distinct ones).

The product of its (nonzero) digits is 2560, while the sum is 28.

The square root of 21850840 is about 4674.4882072800. The cubic root of 21850840 is about 279.5692355920.

The spelling of 21850840 in words is "twenty-one million, eight hundred fifty thousand, eight hundred forty".