20805555 has 8 divisors (see below), whose sum is σ = 33288912. Its totient is φ = 11096288.

The previous prime is 20805553. The next prime is 20805559. The reversal of 20805555 is 55550802.

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 20805555 - 2¹ = 20805553 is a prime.

It is a super-2 number, since 2×20805555² = 865742237716050, which contains 22 as substring.

20805555 is a modest number, since divided by 5555 gives 2080 as remainder.

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 7 ways as a sum of consecutive naturals, for example, 693504 + ... + 693533.

It is an arithmetic number, because the mean of its divisors is an integer number (4161114).

Almost surely, 2^20805555 is an apocalyptic number.

20805555 is a deficient number, since it is larger than the sum of its proper divisors (12483357).

20805555 is a wasteful number, since it uses less digits than its factorization.

20805555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1387045.

The product of its (nonzero) digits is 10000, while the sum is 30.

The square root of 20805555 is about 4561.3106669027. The cubic root of 20805555 is about 275.0382536317.

The spelling of 20805555 in words is "twenty million, eight hundred five thousand, five hundred fifty-five".