166125521661 has 16 divisors (see below), whose sum is σ = 242048798208. Its totient is φ = 100510602800.

The previous prime is 166125521659. The next prime is 166125521669.

166125521661 is nontrivially palindromic in base 10.

It is a cyclic number.

It is not a de Polignac number, because 166125521661 - 2¹ = 166125521659 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166125521669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4268625 + ... + 4307366.

It is an arithmetic number, because the mean of its divisors is an integer number (15128049888).

Almost surely, 2^166125521661 is an apocalyptic number.

166125521661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

166125521661 is a deficient number, since it is larger than the sum of its proper divisors (75923276547).

166125521661 is a wasteful number, since it uses less digits than its factorization.

166125521661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8576592.

The product of its digits is 129600, while the sum is 42.

It can be divided in two parts, 166125 and 521661, that added together give a palindrome (687786).

The spelling of 166125521661 in words is "one hundred sixty-six billion, one hundred twenty-five million, five hundred twenty-one thousand, six hundred sixty-one".