21236668 has 48 divisors (see below), whose sum is σ = 40449024. Its totient is φ = 9737280.

The previous prime is 21236653. The next prime is 21236669. The reversal of 21236668 is 86663212.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21236669) 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 15 ways as a sum of consecutive naturals, for example, 299073 + ... + 299143.

It is an arithmetic number, because the mean of its divisors is an integer number (842688).

Almost surely, 2^21236668 is an apocalyptic number.

It is an amenable number.

21236668 is a deficient number, since it is larger than the sum of its proper divisors (19212356).

21236668 is a wasteful number, since it uses less digits than its factorization.

21236668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 202 (or 200 counting only the distinct ones).

The product of its digits is 20736, while the sum is 34.

The square root of 21236668 is about 4608.3259433334. The cubic root of 21236668 is about 276.9249754460.

It can be divided in two parts, 21236 and 668, that added together give a square (21904 = 148²).

The spelling of 21236668 in words is "twenty-one million, two hundred thirty-six thousand, six hundred sixty-eight".