21385605 has 8 divisors (see below), whose sum is σ = 34216992. Its totient is φ = 11405648.

The previous prime is 21385603. The next prime is 21385627. The reversal of 21385605 is 50658312.

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

It is a cyclic number.

It is not a de Polignac number, because 21385605 - 2¹ = 21385603 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21385603) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 712839 + ... + 712868.

It is an arithmetic number, because the mean of its divisors is an integer number (4277124).

Almost surely, 2^21385605 is an apocalyptic number.

It is an amenable number.

21385605 is a deficient number, since it is larger than the sum of its proper divisors (12831387).

21385605 is a wasteful number, since it uses less digits than its factorization.

21385605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1425715.

The product of its (nonzero) digits is 7200, while the sum is 30.

The square root of 21385605 is about 4624.4572654529. The cubic root of 21385605 is about 277.5708446667.

The spelling of 21385605 in words is "twenty-one million, three hundred eighty-five thousand, six hundred five".