21688334 has 4 divisors (see below), whose sum is σ = 32532504. Its totient is φ = 10844166.

The previous prime is 21688307. The next prime is 21688343. The reversal of 21688334 is 43388612.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a junction number, because it is equal to n+sod(n) for n = 21688294 and 21688303.

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 5422082 + ... + 5422085.

It is an arithmetic number, because the mean of its divisors is an integer number (8133126).

Almost surely, 2^21688334 is an apocalyptic number.

21688334 is a deficient number, since it is larger than the sum of its proper divisors (10844170).

21688334 is a wasteful number, since it uses less digits than its factorization.

21688334 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10844169.

The product of its digits is 27648, while the sum is 35.

The square root of 21688334 is about 4657.0735446201. The cubic root of 21688334 is about 278.8744526624.

It can be divided in two parts, 21688 and 334, that added together give a palindrome (22022).

The spelling of 21688334 in words is "twenty-one million, six hundred eighty-eight thousand, three hundred thirty-four".