21358685 has 4 divisors (see below), whose sum is σ = 25630428. Its totient is φ = 17086944.

The previous prime is 21358669. The next prime is 21358691. The reversal of 21358685 is 58685312.

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

It can be written as a sum of positive squares in 2 ways, for example, as 6895876 + 14462809 = 2626^2 + 3803^2 .

It is a cyclic number.

It is not a de Polignac number, because 21358685 - 2⁴ = 21358669 is a prime.

It is a Duffinian 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 in 3 ways as a sum of consecutive naturals, for example, 2135864 + ... + 2135873.

It is an arithmetic number, because the mean of its divisors is an integer number (6407607).

Almost surely, 2^21358685 is an apocalyptic number.

It is an amenable number.

21358685 is a deficient number, since it is larger than the sum of its proper divisors (4271743).

21358685 is an equidigital number, since it uses as much as digits as its factorization.

21358685 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4271742.

The product of its digits is 57600, while the sum is 38.

The square root of 21358685 is about 4621.5457370884. The cubic root of 21358685 is about 277.4543279000.

The spelling of 21358685 in words is "twenty-one million, three hundred fifty-eight thousand, six hundred eighty-five".