20805550 has 24 divisors (see below), whose sum is σ = 39602376. Its totient is φ = 8127840.

The previous prime is 20805539. The next prime is 20805553. The reversal of 20805550 is 5550802.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20805553) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2689 + ... + 6988.

It is an arithmetic number, because the mean of its divisors is an integer number (1650099).

Almost surely, 2^20805550 is an apocalyptic number.

20805550 is a deficient number, since it is larger than the sum of its proper divisors (18796826).

20805550 is a wasteful number, since it uses less digits than its factorization.

20805550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9732 (or 9727 counting only the distinct ones).

The product of its (nonzero) digits is 2000, while the sum is 25.

The square root of 20805550 is about 4561.3101188145. The cubic root of 20805550 is about 275.0382315992.

The spelling of 20805550 in words is "twenty million, eight hundred five thousand, five hundred fifty".