20816780 has 48 divisors (see below), whose sum is σ = 47628000. Its totient is φ = 7612416.

The previous prime is 20816777. The next prime is 20816791. The reversal of 20816780 is 8761802.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10076 + ... + 11964.

It is an arithmetic number, because the mean of its divisors is an integer number (992250).

Almost surely, 2^20816780 is an apocalyptic number.

20816780 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 20816780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23814000).

20816780 is an abundant number, since it is smaller than the sum of its proper divisors (26811220).

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

20816780 is a wasteful number, since it uses less digits than its factorization.

20816780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1946 (or 1944 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 32.

The square root of 20816780 is about 4562.5409587203. The cubic root of 20816780 is about 275.0877075611.

The spelling of 20816780 in words is "twenty million, eight hundred sixteen thousand, seven hundred eighty".