20657718720 has 168 divisors, whose sum is σ = 72115125264. Its totient is φ = 5426454528.

The previous prime is 20657718673. The next prime is 20657718761. The reversal of 20657718720 is 2781775602.

20657718720 is a `hidden beast` number, since 2 + 0 + 6 + 577 + 1 + 8 + 72 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

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 23 ways as a sum of consecutive naturals, for example, 139432 + ... + 246488.

It is an arithmetic number, because the mean of its divisors is an integer number (429256698).

Almost surely, 2^20657718720 is an apocalyptic number.

20657718720 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 20657718720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36057562632).

20657718720 is an abundant number, since it is smaller than the sum of its proper divisors (51457406544).

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

20657718720 is a wasteful number, since it uses less digits than its factorization.

20657718720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 107147 (or 107134 counting only the distinct ones).

The product of its (nonzero) digits is 329280, while the sum is 45.

The spelling of 20657718720 in words is "twenty billion, six hundred fifty-seven million, seven hundred eighteen thousand, seven hundred twenty".