20571660721161 has 16 divisors (see below), whose sum is σ = 33247128438720. Its totient is φ = 12467673164160.

The previous prime is 20571660721159. The next prime is 20571660721187. The reversal of 20571660721161 is 16112706617502.

20571660721161 is a `hidden beast` number, since 2 + 0 + 5 + 7 + 1 + 6 + 607 + 21 + 16 + 1 = 666.

It is not a de Polignac number, because 20571660721161 - 2¹ = 20571660721159 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20571660721861) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 34632425160 + ... + 34632425753.

It is an arithmetic number, because the mean of its divisors is an integer number (2077945527420).

Almost surely, 2^{20571660721161} is an apocalyptic number.

It is an amenable number.

20571660721161 is a deficient number, since it is larger than the sum of its proper divisors (12675467717559).

20571660721161 is a wasteful number, since it uses less digits than its factorization.

20571660721161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69264850933 (or 69264850927 counting only the distinct ones).

The product of its (nonzero) digits is 211680, while the sum is 45.

The spelling of 20571660721161 in words is "twenty trillion, five hundred seventy-one billion, six hundred sixty million, seven hundred twenty-one thousand, one hundred sixty-one".