166620121 has 2 divisors, whose sum is σ = 166620122. Its totient is φ = 166620120.

The previous prime is 166620107. The next prime is 166620137. The reversal of 166620121 is 121026661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 90250000 + 76370121 = 9500^2 + 8739^2 .

It is a cyclic number.

It is not a de Polignac number, because 166620121 - 2¹⁵ = 166587353 is a prime.

It is not a weakly prime, because it can be changed into another prime (166620161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83310060 + 83310061.

It is an arithmetic number, because the mean of its divisors is an integer number (83310061).

Almost surely, 2^166620121 is an apocalyptic number.

It is an amenable number.

166620121 is a deficient number, since it is larger than the sum of its proper divisors (1).

166620121 is an equidigital number, since it uses as much as digits as its factorization.

166620121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 25.

The square root of 166620121 is about 12908.1416555599. The cubic root of 166620121 is about 550.2699732443.

Adding to 166620121 its reverse (121026661), we get a palindrome (287646782).

The spelling of 166620121 in words is "one hundred sixty-six million, six hundred twenty thousand, one hundred twenty-one".