166720191 has 16 divisors (see below), whose sum is σ = 245427840. Its totient is φ = 99823520.

The previous prime is 166720181. The next prime is 166720219. The reversal of 166720191 is 191027661.

It is a cyclic number.

It is not a de Polignac number, because 166720191 - 2¹⁴ = 166703807 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166720181) 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, 27696 + ... + 33173.

It is an arithmetic number, because the mean of its divisors is an integer number (15339240).

Almost surely, 2^166720191 is an apocalyptic number.

166720191 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

166720191 is a deficient number, since it is larger than the sum of its proper divisors (78707649).

166720191 is a wasteful number, since it uses less digits than its factorization.

166720191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60966.

The product of its (nonzero) digits is 4536, while the sum is 33.

The square root of 166720191 is about 12912.0173094680. The cubic root of 166720191 is about 550.3801129954.

The spelling of 166720191 in words is "one hundred sixty-six million, seven hundred twenty thousand, one hundred ninety-one".