21328685 has 8 divisors (see below), whose sum is σ = 29250816. Its totient is φ = 14625360.

The previous prime is 21328673. The next prime is 21328729. The reversal of 21328685 is 58682312.

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

It is not a de Polignac number, because 21328685 - 2⁴ = 21328669 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (35), and also a Moran number because the ratio is a prime number: 609391 = 21328685 / (2 + 1 + 3 + 2 + 8 + 6 + 8 + 5).

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 7 ways as a sum of consecutive naturals, for example, 304661 + ... + 304730.

It is an arithmetic number, because the mean of its divisors is an integer number (3656352).

Almost surely, 2^21328685 is an apocalyptic number.

It is an amenable number.

21328685 is a deficient number, since it is larger than the sum of its proper divisors (7922131).

21328685 is an equidigital number, since it uses as much as digits as its factorization.

21328685 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 609403.

The product of its digits is 23040, while the sum is 35.

The square root of 21328685 is about 4618.2989292596. The cubic root of 21328685 is about 277.3243646875.

The spelling of 21328685 in words is "twenty-one million, three hundred twenty-eight thousand, six hundred eighty-five".