20555778720 has 96 divisors (see below), whose sum is σ = 64811916288. Its totient is φ = 5476359168.

The previous prime is 20555778703. The next prime is 20555778721. The reversal of 20555778720 is 2787755502.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a self number, because there is not a number n which added to its sum of digits gives 20555778720.

It is not an unprimeable number, because it can be changed into a prime (20555778721) by changing a digit.

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, 502062 + ... + 541458.

It is an arithmetic number, because the mean of its divisors is an integer number (675124128).

Almost surely, 2^20555778720 is an apocalyptic number.

20555778720 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 20555778720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32405958144).

20555778720 is an abundant number, since it is smaller than the sum of its proper divisors (44256137568).

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

20555778720 is a wasteful number, since it uses less digits than its factorization.

20555778720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40502 (or 40494 counting only the distinct ones).

The product of its (nonzero) digits is 1372000, while the sum is 48.

The spelling of 20555778720 in words is "twenty billion, five hundred fifty-five million, seven hundred seventy-eight thousand, seven hundred twenty".