166081261 has 4 divisors (see below), whose sum is σ = 174822400. Its totient is φ = 157340124.

The previous prime is 166081259. The next prime is 166081273. The reversal of 166081261 is 162180661.

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 166081261 - 2¹ = 166081259 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 (166081061) 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, 4370541 + ... + 4370578.

It is an arithmetic number, because the mean of its divisors is an integer number (43705600).

Almost surely, 2^166081261 is an apocalyptic number.

It is an amenable number.

166081261 is a deficient number, since it is larger than the sum of its proper divisors (8741139).

166081261 is an equidigital number, since it uses as much as digits as its factorization.

166081261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8741138.

The product of its (nonzero) digits is 3456, while the sum is 31.

The square root of 166081261 is about 12887.2518792798. The cubic root of 166081261 is about 549.6761299863.

The spelling of 166081261 in words is "one hundred sixty-six million, eighty-one thousand, two hundred sixty-one".