165856801 has 4 divisors (see below), whose sum is σ = 180934704. Its totient is φ = 150778900.

The previous prime is 165856783. The next prime is 165856819. The reversal of 165856801 is 108658561.

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: 108658561 = 11 ⋅9878051.

It is an interprime number because it is at equal distance from previous prime (165856783) and next prime (165856819).

It is a cyclic number.

It is not a de Polignac number, because 165856801 - 2¹⁵ = 165824033 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165856001) 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, 7538935 + ... + 7538956.

It is an arithmetic number, because the mean of its divisors is an integer number (45233676).

Almost surely, 2^165856801 is an apocalyptic number.

165856801 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

165856801 is a deficient number, since it is larger than the sum of its proper divisors (15077903).

165856801 is a wasteful number, since it uses less digits than its factorization.

165856801 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15077902.

The product of its (nonzero) digits is 57600, while the sum is 40.

The square root of 165856801 is about 12878.5403287795. The cubic root of 165856801 is about 549.4283879507.

The spelling of 165856801 in words is "one hundred sixty-five million, eight hundred fifty-six thousand, eight hundred one".