20305680 has 160 divisors (see below), whose sum is σ = 68269440. Its totient is φ = 4976640.

The previous prime is 20305673. The next prime is 20305693. The reversal of 20305680 is 8650302.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 20305680.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 278124 + ... + 278196.

It is an arithmetic number, because the mean of its divisors is an integer number (426684).

Almost surely, 2^20305680 is an apocalyptic number.

20305680 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 20305680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34134720).

20305680 is an abundant number, since it is smaller than the sum of its proper divisors (47963760).

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

20305680 is a wasteful number, since it uses less digits than its factorization.

20305680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 169 (or 163 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 24.

The square root of 20305680 is about 4506.1824197429. The cubic root of 20305680 is about 272.8176807339.

Adding to 20305680 its reverse (8650302), we get a palindrome (28955982).

The spelling of 20305680 in words is "twenty million, three hundred five thousand, six hundred eighty".