21328605 has 24 divisors (see below), whose sum is σ = 37229400. Its totient is φ = 11295360.

The previous prime is 21328603. The next prime is 21328609. The reversal of 21328605 is 50682312.

21328605 is a `hidden beast` number, since 21 + 32 + 8 + 605 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 480249 + 20848356 = 693^2 + 4566^2 .

It is not a de Polignac number, because 21328605 - 2¹ = 21328603 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21328603) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5115 + ... + 8295.

It is an arithmetic number, because the mean of its divisors is an integer number (1551225).

Almost surely, 2^21328605 is an apocalyptic number.

It is an amenable number.

21328605 is a deficient number, since it is larger than the sum of its proper divisors (15900795).

21328605 is a wasteful number, since it uses less digits than its factorization.

21328605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3341 (or 3338 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The square root of 21328605 is about 4618.2902680538. The cubic root of 21328605 is about 277.3240179561.

The spelling of 21328605 in words is "twenty-one million, three hundred twenty-eight thousand, six hundred five".