166521001 has 8 divisors (see below), whose sum is σ = 176795784. Its totient is φ = 156299520.

The previous prime is 166520999. The next prime is 166521007. The reversal of 166521001 is 100125661.

It can be written as a sum of positive squares in 4 ways, for example, as 7155625 + 159365376 = 2675^2 + 12624^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 166521001 - 2¹ = 166520999 is a prime.

It is not an unprimeable number, because it can be changed into a prime (166521007) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6790 + ... + 19471.

It is an arithmetic number, because the mean of its divisors is an integer number (22099473).

Almost surely, 2^166521001 is an apocalyptic number.

It is an amenable number.

166521001 is a deficient number, since it is larger than the sum of its proper divisors (10274783).

166521001 is a wasteful number, since it uses less digits than its factorization.

166521001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26651.

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 166521001 is about 12904.3016471253. The cubic root of 166521001 is about 550.1608356071.

Adding to 166521001 its reverse (100125661), we get a palindrome (266646662).

The spelling of 166521001 in words is "one hundred sixty-six million, five hundred twenty-one thousand, one".