20805120 has 320 divisors, whose sum is σ = 86423040. Its totient is φ = 4644864.

The previous prime is 20805119. The next prime is 20805121. The reversal of 20805120 is 2150802.

It is an interprime number because it is at equal distance from previous prime (20805119) and next prime (20805121).

It is a tau number, because it is divible by the number of its divisors (320).

It is a super-3 number, since 3×20805120³ (a number of 23 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 20805093 and 20805102.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20805121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 483819 + ... + 483861.

It is an arithmetic number, because the mean of its divisors is an integer number (270072).

Almost surely, 2^20805120 is an apocalyptic number.

20805120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20805120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43211520).

20805120 is an abundant number, since it is smaller than the sum of its proper divisors (65617920).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20805120 is an equidigital number, since it uses as much as digits as its factorization.

20805120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82 (or 60 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

The square root of 20805120 is about 4561.2629829906. The cubic root of 20805120 is about 275.0363367963.

Adding to 20805120 its reverse (2150802), we get a palindrome (22955922).

The spelling of 20805120 in words is "twenty million, eight hundred five thousand, one hundred twenty".