2161155065121 has 12 divisors (see below), whose sum is σ = 3361796768148. Its totient is φ = 1329941578464.

The previous prime is 2161155065107. The next prime is 2161155065171. The reversal of 2161155065121 is 1215605511612.

2161155065121 is a `hidden beast` number, since 2 + 16 + 1 + 15 + 506 + 5 + 121 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 1086430982400 + 1074724082721 = 1042320^2 + 1036689^2 .

It is not a de Polignac number, because 2161155065121 - 2¹⁴ = 2161155048737 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2161155065171) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9235705290 + ... + 9235705523.

It is an arithmetic number, because the mean of its divisors is an integer number (280149730679).

Almost surely, 2^{2161155065121} is an apocalyptic number.

It is an amenable number.

2161155065121 is a deficient number, since it is larger than the sum of its proper divisors (1200641703027).

2161155065121 is a wasteful number, since it uses less digits than its factorization.

2161155065121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18471410832 (or 18471410829 counting only the distinct ones).

The product of its (nonzero) digits is 18000, while the sum is 36.

The spelling of 2161155065121 in words is "two trillion, one hundred sixty-one billion, one hundred fifty-five million, sixty-five thousand, one hundred twenty-one".