21181136 has 40 divisors (see below), whose sum is σ = 42854400. Its totient is φ = 10129280.

The previous prime is 21181117. The next prime is 21181157. The reversal of 21181136 is 63118112.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 88505 + ... + 88743.

It is an arithmetic number, because the mean of its divisors is an integer number (1071360).

Almost surely, 2^21181136 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21181136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21427200).

21181136 is an abundant number, since it is smaller than the sum of its proper divisors (21673264).

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

21181136 is a wasteful number, since it uses less digits than its factorization.

21181136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 467 (or 461 counting only the distinct ones).

The product of its digits is 288, while the sum is 23.

The square root of 21181136 is about 4602.2968178943. The cubic root of 21181136 is about 276.6833866768.

Adding to 21181136 its reverse (63118112), we get a palindrome (84299248).

The spelling of 21181136 in words is "twenty-one million, one hundred eighty-one thousand, one hundred thirty-six".