21853140 has 72 divisors (see below), whose sum is σ = 63393120. Its totient is φ = 5624640.

The previous prime is 21853129. The next prime is 21853141. The reversal of 21853140 is 4135812.

It is a self number, because there is not a number n which added to its sum of digits gives 21853140.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21853141) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 57471 + ... + 57849.

It is an arithmetic number, because the mean of its divisors is an integer number (880460).

Almost surely, 2^21853140 is an apocalyptic number.

21853140 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 21853140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31696560).

21853140 is an abundant number, since it is smaller than the sum of its proper divisors (41539980).

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

21853140 is a wasteful number, since it uses less digits than its factorization.

21853140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 453 (or 420 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 24.

The square root of 21853140 is about 4674.7342170438. The cubic root of 21853140 is about 279.5790443176.

Adding to 21853140 its reverse (4135812), we get a palindrome (25988952).

The spelling of 21853140 in words is "twenty-one million, eight hundred fifty-three thousand, one hundred forty".