21171005205066 has 24 divisors (see below), whose sum is σ = 46123939523844. Its totient is φ = 7018012774080.

The previous prime is 21171005205037. The next prime is 21171005205067. The reversal of 21171005205066 is 66050250017112.

21171005205066 is a `hidden beast` number, since 2 + 1 + 1 + 71 + 0 + 0 + 520 + 5 + 0 + 66 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 19864590494841 + 1306414710225 = 4456971^2 + 1142985^2 .

It is a super-2 number, since 2×21171005205066² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21171005205066.

It is not an unprimeable number, because it can be changed into a prime (21171005205067) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 3249076731 + ... + 3249083246.

Almost surely, 2^{21171005205066} is an apocalyptic number.

21171005205066 is an abundant number, since it is smaller than the sum of its proper divisors (24952934318778).

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

21171005205066 is a wasteful number, since it uses less digits than its factorization.

21171005205066 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6498160166 (or 6498160163 counting only the distinct ones).

The product of its (nonzero) digits is 25200, while the sum is 36.

The spelling of 21171005205066 in words is "twenty-one trillion, one hundred seventy-one billion, five million, two hundred five thousand, sixty-six".