166115655506565 has 48 divisors (see below), whose sum is σ = 306917200278000. Its totient is φ = 82823923562496.

The previous prime is 166115655506533. The next prime is 166115655506569. The reversal of 166115655506565 is 565605556511661.

166115655506565 is a `hidden beast` number, since 1 + 6 + 6 + 1 + 1 + 5 + 65 + 5 + 5 + 0 + 6 + 565 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 4101426939204 + 162014228567361 = 2025198^2 + 12728481^2 .

It is not a de Polignac number, because 166115655506565 - 2⁵ = 166115655506533 is a prime.

It is a super-2 number, since 2×166115655506565² (a number of 29 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166115655506569) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 728559330 + ... + 728787299.

It is an arithmetic number, because the mean of its divisors is an integer number (6394108339125).

Almost surely, 2^{166115655506565} is an apocalyptic number.

166115655506565 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

166115655506565 is a deficient number, since it is larger than the sum of its proper divisors (140801544771435).

166115655506565 is a wasteful number, since it uses less digits than its factorization.

166115655506565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1457346806 (or 1457346803 counting only the distinct ones).

The product of its (nonzero) digits is 121500000, while the sum is 63.

The spelling of 166115655506565 in words is "one hundred sixty-six trillion, one hundred fifteen billion, six hundred fifty-five million, five hundred six thousand, five hundred sixty-five".