166891281 has 4 divisors (see below), whose sum is σ = 222521712. Its totient is φ = 111260852.

The previous prime is 166891271. The next prime is 166891301. The reversal of 166891281 is 182198661.

166891281 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 166891281 - 2¹³ = 166883089 is a prime.

It is a super-2 number, since 2×166891281² = 55705399347641922, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (166891271) 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, 27815211 + ... + 27815216.

It is an arithmetic number, because the mean of its divisors is an integer number (55630428).

Almost surely, 2^166891281 is an apocalyptic number.

It is an amenable number.

166891281 is a deficient number, since it is larger than the sum of its proper divisors (55630431).

166891281 is an equidigital number, since it uses as much as digits as its factorization.

166891281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55630430.

The product of its digits is 41472, while the sum is 42.

The square root of 166891281 is about 12918.6408340816. The cubic root of 166891281 is about 550.5683172364.

The spelling of 166891281 in words is "one hundred sixty-six million, eight hundred ninety-one thousand, two hundred eighty-one".