21086685 has 12 divisors (see below), whose sum is σ = 36550332. Its totient is φ = 11246208.

The previous prime is 21086671. The next prime is 21086687. The reversal of 21086685 is 58668012.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 9018009 + 12068676 = 3003^2 + 3474^2 .

It is not a de Polignac number, because 21086685 - 2²¹ = 18989533 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21086687) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 234252 + ... + 234341.

It is an arithmetic number, because the mean of its divisors is an integer number (3045861).

Almost surely, 2^21086685 is an apocalyptic number.

It is an amenable number.

21086685 is a deficient number, since it is larger than the sum of its proper divisors (15463647).

21086685 is a wasteful number, since it uses less digits than its factorization.

21086685 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 468604 (or 468601 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

The square root of 21086685 is about 4592.0240635258. The cubic root of 21086685 is about 276.2715113297.

The spelling of 21086685 in words is "twenty-one million, eighty-six thousand, six hundred eighty-five".