20505551660 has 24 divisors (see below), whose sum is σ = 46976355216. Its totient is φ = 7456564160.

The previous prime is 20505551641. The next prime is 20505551669. The reversal of 20505551660 is 6615550502.

It is a self number, because there is not a number n which added to its sum of digits gives 20505551660.

It is not an unprimeable number, because it can be changed into a prime (20505551669) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 46603307 + ... + 46603746.

It is an arithmetic number, because the mean of its divisors is an integer number (1957348134).

Almost surely, 2^20505551660 is an apocalyptic number.

20505551660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20505551660 is an abundant number, since it is smaller than the sum of its proper divisors (26470803556).

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

20505551660 is a wasteful number, since it uses less digits than its factorization.

20505551660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 93207073 (or 93207071 counting only the distinct ones).

The product of its (nonzero) digits is 45000, while the sum is 35.

The spelling of 20505551660 in words is "twenty billion, five hundred five million, five hundred fifty-one thousand, six hundred sixty".