166805251 has 4 divisors (see below), whose sum is σ = 166834312. Its totient is φ = 166776192.

The previous prime is 166805239. The next prime is 166805273. The reversal of 166805251 is 152508661.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 166805251 - 2²¹ = 164708099 is a prime.

It is a super-2 number, since 2×166805251² = 55647983522346002, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166805201) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2721 + ... + 18466.

It is an arithmetic number, because the mean of its divisors is an integer number (41708578).

Almost surely, 2^166805251 is an apocalyptic number.

166805251 is a deficient number, since it is larger than the sum of its proper divisors (29061).

166805251 is an equidigital number, since it uses as much as digits as its factorization.

166805251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29060.

The product of its (nonzero) digits is 14400, while the sum is 34.

The square root of 166805251 is about 12915.3107202266. The cubic root of 166805251 is about 550.4736976871.

The spelling of 166805251 in words is "one hundred sixty-six million, eight hundred five thousand, two hundred fifty-one".