166061561 has 4 divisors (see below), whose sum is σ = 169194852. Its totient is φ = 162928272.

The previous prime is 166061557. The next prime is 166061563. The reversal of 166061561 is 165160661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 165160661 = 17 ⋅9715333.

It can be written as a sum of positive squares in 2 ways, for example, as 125865961 + 40195600 = 11219^2 + 6340^2 .

It is a cyclic number.

It is not a de Polignac number, because 166061561 - 2² = 166061557 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166061563) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1566566 + ... + 1566671.

It is an arithmetic number, because the mean of its divisors is an integer number (42298713).

Almost surely, 2^166061561 is an apocalyptic number.

It is an amenable number.

166061561 is a deficient number, since it is larger than the sum of its proper divisors (3133291).

166061561 is an equidigital number, since it uses as much as digits as its factorization.

166061561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3133290.

The product of its (nonzero) digits is 6480, while the sum is 32.

The square root of 166061561 is about 12886.4875353992. The cubic root of 166061561 is about 549.6543955496.

The spelling of 166061561 in words is "one hundred sixty-six million, sixty-one thousand, five hundred sixty-one".