20918715780 has 96 divisors (see below), whose sum is σ = 60057002880. Its totient is φ = 5437189120.

The previous prime is 20918715767. The next prime is 20918715799. The reversal of 20918715780 is 8751781902.

It is a happy 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 31 ways as a sum of consecutive naturals, for example, 3138091 + ... + 3144749.

It is an arithmetic number, because the mean of its divisors is an integer number (625593780).

Almost surely, 2^20918715780 is an apocalyptic number.

20918715780 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 20918715780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30028501440).

20918715780 is an abundant number, since it is smaller than the sum of its proper divisors (39138287100).

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

20918715780 is a wasteful number, since it uses less digits than its factorization.

20918715780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7989 (or 7987 counting only the distinct ones).

The product of its (nonzero) digits is 282240, while the sum is 48.

The spelling of 20918715780 in words is "twenty billion, nine hundred eighteen million, seven hundred fifteen thousand, seven hundred eighty".