20684780 has 12 divisors (see below), whose sum is σ = 43438080. Its totient is φ = 8273904.

The previous prime is 20684779. The next prime is 20684791. The reversal of 20684780 is 8748602.

It is a self number, because there is not a number n which added to its sum of digits gives 20684780.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 517100 + ... + 517139.

It is an arithmetic number, because the mean of its divisors is an integer number (3619840).

Almost surely, 2^20684780 is an apocalyptic number.

20684780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20684780 is an abundant number, since it is smaller than the sum of its proper divisors (22753300).

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

20684780 is a wasteful number, since it uses less digits than its factorization.

20684780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1034248 (or 1034246 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 35.

The square root of 20684780 is about 4548.0523303937. The cubic root of 20684780 is about 274.5050269870.

The spelling of 20684780 in words is "twenty million, six hundred eighty-four thousand, seven hundred eighty".