21686086 has 4 divisors (see below), whose sum is σ = 32529132. Its totient is φ = 10843042.

The previous prime is 21686057. The next prime is 21686111. The reversal of 21686086 is 68068612.

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 (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5421520 + ... + 5421523.

It is an arithmetic number, because the mean of its divisors is an integer number (8132283).

Almost surely, 2^21686086 is an apocalyptic number.

21686086 is a deficient number, since it is larger than the sum of its proper divisors (10843046).

21686086 is a wasteful number, since it uses less digits than its factorization.

21686086 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10843045.

The product of its (nonzero) digits is 27648, while the sum is 37.

The square root of 21686086 is about 4656.8321850803. The cubic root of 21686086 is about 278.8648171992.

The spelling of 21686086 in words is "twenty-one million, six hundred eighty-six thousand, eighty-six".