20661761758728 has 16 divisors (see below), whose sum is σ = 51654404396880. Its totient is φ = 6887253919568.

The previous prime is 20661761758657. The next prime is 20661761758777. The reversal of 20661761758728 is 82785716716602.

It is a super-3 number, since 3×20661761758728³ (a number of 41 digits) contains 333 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 430453369950 + ... + 430453369997.

It is an arithmetic number, because the mean of its divisors is an integer number (3228400274805).

Almost surely, 2^{20661761758728} is an apocalyptic number.

It is an amenable number.

20661761758728 is an abundant number, since it is smaller than the sum of its proper divisors (30992642638152).

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

20661761758728 is a wasteful number, since it uses less digits than its factorization.

20661761758728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 860906739956 (or 860906739952 counting only the distinct ones).

The product of its (nonzero) digits is 94832640, while the sum is 66.

The spelling of 20661761758728 in words is "twenty trillion, six hundred sixty-one billion, seven hundred sixty-one million, seven hundred fifty-eight thousand, seven hundred twenty-eight".