1221166165161 has 64 divisors (see below), whose sum is σ = 1808212377600. Its totient is φ = 729550488576.

The previous prime is 1221166165081. The next prime is 1221166165223. The reversal of 1221166165161 is 1615616611221.

It is not a de Polignac number, because 1221166165161 - 2¹⁴ = 1221166148777 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1221166165061) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 103632076 + ... + 103643858.

It is an arithmetic number, because the mean of its divisors is an integer number (28253318400).

Almost surely, 2^{1221166165161} is an apocalyptic number.

It is an amenable number.

1221166165161 is a deficient number, since it is larger than the sum of its proper divisors (587046212439).

1221166165161 is a wasteful number, since it uses less digits than its factorization.

1221166165161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12798.

The product of its digits is 25920, while the sum is 39.

The spelling of 1221166165161 in words is "one trillion, two hundred twenty-one billion, one hundred sixty-six million, one hundred sixty-five thousand, one hundred sixty-one".