20928805 has 8 divisors (see below), whose sum is σ = 25298712. Its totient is φ = 16620288.

The previous prime is 20928793. The next prime is 20928811. The reversal of 20928805 is 50882902.

It can be written as a sum of positive squares in 4 ways, for example, as 804609 + 20124196 = 897^2 + 4486^2 .

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 20928805 - 2²¹ = 18831653 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14592 + ... + 15961.

It is an arithmetic number, because the mean of its divisors is an integer number (3162339).

Almost surely, 2^20928805 is an apocalyptic number.

It is an amenable number.

20928805 is a deficient number, since it is larger than the sum of its proper divisors (4369907).

20928805 is a wasteful number, since it uses less digits than its factorization.

20928805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30695.

The product of its (nonzero) digits is 11520, while the sum is 34.

The square root of 20928805 is about 4574.8010885720. The cubic root of 20928805 is about 275.5802843083.

It can be divided in two parts, 20 and 928805, that multiplied together give a square (18576100 = 4310²).

The spelling of 20928805 in words is "twenty million, nine hundred twenty-eight thousand, eight hundred five".