21133860 has 144 divisors (see below), whose sum is σ = 67568256. Its totient is φ = 4928000.

The previous prime is 21133841. The next prime is 21133867. The reversal of 21133860 is 6833112.

21133860 = T₈₄₉ + T₈₅₀ + ... + T₉₀₃.

It is a self number, because there is not a number n which added to its sum of digits gives 21133860.

It is not an unprimeable number, because it can be changed into a prime (21133867) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 297625 + ... + 297695.

It is an arithmetic number, because the mean of its divisors is an integer number (469224).

Almost surely, 2^21133860 is an apocalyptic number.

21133860 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 21133860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33784128).

21133860 is an abundant number, since it is smaller than the sum of its proper divisors (46434396).

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

21133860 is a wasteful number, since it uses less digits than its factorization.

21133860 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 146 (or 133 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 24.

The square root of 21133860 is about 4597.1578176086. The cubic root of 21133860 is about 276.4773821815.

Adding to 21133860 its reverse (6833112), we get a palindrome (27966972).

The spelling of 21133860 in words is "twenty-one million, one hundred thirty-three thousand, eight hundred sixty".