21856438 has 8 divisors (see below), whose sum is σ = 32868432. Its totient is φ = 10900296.

The previous prime is 21856423. The next prime is 21856451. The reversal of 21856438 is 83465812.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 21856397 and 21856406.

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 in 3 ways as a sum of consecutive naturals, for example, 12970 + ... + 14557.

It is an arithmetic number, because the mean of its divisors is an integer number (4108554).

Almost surely, 2^21856438 is an apocalyptic number.

21856438 is a deficient number, since it is larger than the sum of its proper divisors (11011994).

21856438 is a wasteful number, since it uses less digits than its factorization.

21856438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27926.

The product of its digits is 46080, while the sum is 37.

The square root of 21856438 is about 4675.0869510630. The cubic root of 21856438 is about 279.5931079763.

The spelling of 21856438 in words is "twenty-one million, eight hundred fifty-six thousand, four hundred thirty-eight".