21216136 has 32 divisors (see below), whose sum is σ = 42717240. Its totient is φ = 9842688.

The previous prime is 21216127. The next prime is 21216137. The reversal of 21216136 is 63161212.

It can be written as a sum of positive squares in 4 ways, for example, as 16402500 + 4813636 = 4050^2 + 2194^2 .

It is not an unprimeable number, because it can be changed into a prime (21216137) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8860 + ... + 10996.

Almost surely, 2^21216136 is an apocalyptic number.

It is an amenable number.

21216136 is an abundant number, since it is smaller than the sum of its proper divisors (21501104).

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

21216136 is a wasteful number, since it uses less digits than its factorization.

21216136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2233 (or 2229 counting only the distinct ones).

The product of its digits is 432, while the sum is 22.

The square root of 21216136 is about 4606.0976976178. The cubic root of 21216136 is about 276.8357012879.

Adding to 21216136 its reverse (63161212), we get a palindrome (84377348).

The spelling of 21216136 in words is "twenty-one million, two hundred sixteen thousand, one hundred thirty-six".