20908645 has 16 divisors (see below), whose sum is σ = 26634240. Its totient is φ = 15712704.

The previous prime is 20908639. The next prime is 20908649. The reversal of 20908645 is 54680902.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 20908645 - 2³ = 20908637 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20908645.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20908649) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 11199 + ... + 12931.

It is an arithmetic number, because the mean of its divisors is an integer number (1664640).

Almost surely, 2^20908645 is an apocalyptic number.

It is an amenable number.

20908645 is a deficient number, since it is larger than the sum of its proper divisors (5725595).

20908645 is a wasteful number, since it uses less digits than its factorization.

20908645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1884.

The product of its (nonzero) digits is 17280, while the sum is 34.

The square root of 20908645 is about 4572.5971832209. The cubic root of 20908645 is about 275.4917702029.

The spelling of 20908645 in words is "twenty million, nine hundred eight thousand, six hundred forty-five".