21056686 has 16 divisors (see below), whose sum is σ = 36288864. Its totient is φ = 8976384.

The previous prime is 21056681. The next prime is 21056689. The reversal of 21056686 is 68665012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21056681) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 1195 + ... + 6598.

It is an arithmetic number, because the mean of its divisors is an integer number (2268054).

Almost surely, 2^21056686 is an apocalyptic number.

21056686 is a deficient number, since it is larger than the sum of its proper divisors (15232178).

21056686 is a wasteful number, since it uses less digits than its factorization.

21056686 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7995.

The product of its (nonzero) digits is 17280, while the sum is 34.

The square root of 21056686 is about 4588.7564764324. The cubic root of 21056686 is about 276.1404364764.

The spelling of 21056686 in words is "twenty-one million, fifty-six thousand, six hundred eighty-six".