166723309 has 16 divisors (see below), whose sum is σ = 180335680. Its totient is φ = 153653760.

The previous prime is 166723279. The next prime is 166723331. The reversal of 166723309 is 903327661.

It is not a de Polignac number, because 166723309 - 2¹⁵ = 166690541 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166723339) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 111682 + ... + 113164.

It is an arithmetic number, because the mean of its divisors is an integer number (11270980).

Almost surely, 2^166723309 is an apocalyptic number.

166723309 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

166723309 is a deficient number, since it is larger than the sum of its proper divisors (13612371).

166723309 is a wasteful number, since it uses less digits than its factorization.

166723309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1660.

The product of its (nonzero) digits is 40824, while the sum is 37.

The square root of 166723309 is about 12912.1380491381. The cubic root of 166723309 is about 550.3835440426.

It can be divided in two parts, 1667 and 23309, that added together give a triangular number (24976 = T₂₂₃).

The spelling of 166723309 in words is "one hundred sixty-six million, seven hundred twenty-three thousand, three hundred nine".