165664905281 has 4 divisors (see below), whose sum is σ = 165685307952. Its totient is φ = 165644502612.

The previous prime is 165664905257. The next prime is 165664905283. The reversal of 165664905281 is 182509466561.

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, and also an emirpimes, since its reverse is a distinct semiprime: 182509466561 = 281 ⋅649499881.

It is a cyclic number.

It is not a de Polignac number, because 165664905281 - 2¹⁰ = 165664904257 is a prime.

It is a super-2 number, since 2×165664905281² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165664905283) 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, 10189151 + ... + 10205396.

It is an arithmetic number, because the mean of its divisors is an integer number (41421326988).

Almost surely, 2^165664905281 is an apocalyptic number.

It is an amenable number.

165664905281 is a deficient number, since it is larger than the sum of its proper divisors (20402671).

165664905281 is an equidigital number, since it uses as much as digits as its factorization.

165664905281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20402670.

The product of its (nonzero) digits is 3110400, while the sum is 53.

The spelling of 165664905281 in words is "one hundred sixty-five billion, six hundred sixty-four million, nine hundred five thousand, two hundred eighty-one".