21181116 has 48 divisors (see below), whose sum is σ = 57093120. Its totient is φ = 6040320.

The previous prime is 21181109. The next prime is 21181117. The reversal of 21181116 is 61118112.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21181092 and 21181101.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21181117) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2476 + ... + 6963.

It is an arithmetic number, because the mean of its divisors is an integer number (1189440).

Almost surely, 2^21181116 is an apocalyptic number.

It is an amenable number.

21181116 is an abundant number, since it is smaller than the sum of its proper divisors (35912004).

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

21181116 is a wasteful number, since it uses less digits than its factorization.

21181116 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9474 (or 9472 counting only the distinct ones).

The product of its digits is 96, while the sum is 21.

The square root of 21181116 is about 4602.2946450657. The cubic root of 21181116 is about 276.6832995920.

Adding to 21181116 its reverse (61118112), we get a palindrome (82299228).

The spelling of 21181116 in words is "twenty-one million, one hundred eighty-one thousand, one hundred sixteen".