21667838 has 4 divisors (see below), whose sum is σ = 32501760. Its totient is φ = 10833918.

The previous prime is 21667837. The next prime is 21667859. The reversal of 21667838 is 83876612.

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 = 21667795 and 21667804.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21667837) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5416958 + ... + 5416961.

It is an arithmetic number, because the mean of its divisors is an integer number (8125440).

Almost surely, 2^21667838 is an apocalyptic number.

21667838 is a deficient number, since it is larger than the sum of its proper divisors (10833922).

21667838 is a wasteful number, since it uses less digits than its factorization.

21667838 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10833921.

The product of its digits is 96768, while the sum is 41.

The square root of 21667838 is about 4654.8725009392. The cubic root of 21667838 is about 278.7865772750.

The spelling of 21667838 in words is "twenty-one million, six hundred sixty-seven thousand, eight hundred thirty-eight".