21856678 has 4 divisors (see below), whose sum is σ = 32785020. Its totient is φ = 10928338.

The previous prime is 21856663. The next prime is 21856697. The reversal of 21856678 is 87665812.

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

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, 5464168 + ... + 5464171.

It is an arithmetic number, because the mean of its divisors is an integer number (8196255).

Almost surely, 2^21856678 is an apocalyptic number.

21856678 is a deficient number, since it is larger than the sum of its proper divisors (10928342).

21856678 is a wasteful number, since it uses less digits than its factorization.

21856678 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10928341.

The product of its digits is 161280, while the sum is 43.

The square root of 21856678 is about 4675.1126189644. The cubic root of 21856678 is about 279.5941313529.

The spelling of 21856678 in words is "twenty-one million, eight hundred fifty-six thousand, six hundred seventy-eight".