21086986 has 8 divisors (see below), whose sum is σ = 31710564. Its totient is φ = 10516800.

The previous prime is 21086981. The next prime is 21087019. The reversal of 21086986 is 68968012.

It can be written as a sum of positive squares in 2 ways, for example, as 12496225 + 8590761 = 3535^2 + 2931^2 .

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

It is not an unprimeable number, because it can be changed into a prime (21086981) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12345 + ... + 13948.

Almost surely, 2^21086986 is an apocalyptic number.

21086986 is a deficient number, since it is larger than the sum of its proper divisors (10623578).

21086986 is a wasteful number, since it uses less digits than its factorization.

21086986 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26696.

The product of its (nonzero) digits is 41472, while the sum is 40.

The square root of 21086986 is about 4592.0568376273. The cubic root of 21086986 is about 276.2728258611.

The spelling of 21086986 in words is "twenty-one million, eighty-six thousand, nine hundred eighty-six".