21164236 has 12 divisors (see below), whose sum is σ = 37419928. Its totient is φ = 10472832.

The previous prime is 21164189. The next prime is 21164237. The reversal of 21164236 is 63246112.

It is a self number, because there is not a number n which added to its sum of digits gives 21164236.

It is not an unprimeable number, because it can be changed into a prime (21164237) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26886 + ... + 27661.

Almost surely, 2^21164236 is an apocalyptic number.

It is an amenable number.

21164236 is a deficient number, since it is larger than the sum of its proper divisors (16255692).

21164236 is a wasteful number, since it uses less digits than its factorization.

21164236 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54648 (or 54646 counting only the distinct ones).

The product of its digits is 1728, while the sum is 25.

The square root of 21164236 is about 4600.4604117414. The cubic root of 21164236 is about 276.6097804044.

The spelling of 21164236 in words is "twenty-one million, one hundred sixty-four thousand, two hundred thirty-six".