166520281 has 4 divisors (see below), whose sum is σ = 168048100. Its totient is φ = 164992464.

The previous prime is 166520273. The next prime is 166520293. The reversal of 166520281 is 182025661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 182025661 = 3631 ⋅50131.

It can be written as a sum of positive squares in 2 ways, for example, as 102839881 + 63680400 = 10141^2 + 7980^2 .

It is a cyclic number.

It is not a de Polignac number, because 166520281 - 2³ = 166520273 is a prime.

It is a super-2 number, since 2×166520281² = 55458007968637922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166520261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 763746 + ... + 763963.

It is an arithmetic number, because the mean of its divisors is an integer number (42012025).

Almost surely, 2^166520281 is an apocalyptic number.

It is an amenable number.

166520281 is a deficient number, since it is larger than the sum of its proper divisors (1527819).

166520281 is a wasteful number, since it uses less digits than its factorization.

166520281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1527818.

The product of its (nonzero) digits is 5760, while the sum is 31.

The square root of 166520281 is about 12904.2737494212. The cubic root of 166520281 is about 550.1600426814.

The spelling of 166520281 in words is "one hundred sixty-six million, five hundred twenty thousand, two hundred eighty-one".