21106678 has 4 divisors (see below), whose sum is σ = 31660020. Its totient is φ = 10553338.

The previous prime is 21106669. The next prime is 21106717. The reversal of 21106678 is 87660112.

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

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5276668 + ... + 5276671.

It is an arithmetic number, because the mean of its divisors is an integer number (7915005).

Almost surely, 2^21106678 is an apocalyptic number.

21106678 is a deficient number, since it is larger than the sum of its proper divisors (10553342).

21106678 is a wasteful number, since it uses less digits than its factorization.

21106678 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10553341.

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 21106678 is about 4594.2004745113. The cubic root of 21106678 is about 276.3587978737.

The spelling of 21106678 in words is "twenty-one million, one hundred six thousand, six hundred seventy-eight".