166621907 has 4 divisors (see below), whose sum is σ = 172367520. Its totient is φ = 160876296.

The previous prime is 166621891. The next prime is 166621921. The reversal of 166621907 is 709126661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 709126661 = 17 ⋅41713333.

It is a cyclic number.

It is not a de Polignac number, because 166621907 - 2⁴ = 166621891 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166621997) 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, 2872763 + ... + 2872820.

It is an arithmetic number, because the mean of its divisors is an integer number (43091880).

Almost surely, 2^166621907 is an apocalyptic number.

166621907 is a deficient number, since it is larger than the sum of its proper divisors (5745613).

166621907 is an equidigital number, since it uses as much as digits as its factorization.

166621907 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5745612.

The product of its (nonzero) digits is 27216, while the sum is 38.

The square root of 166621907 is about 12908.2108365180. The cubic root of 166621907 is about 550.2719393507.

The spelling of 166621907 in words is "one hundred sixty-six million, six hundred twenty-one thousand, nine hundred seven".