165906401 has 4 divisors (see below), whose sum is σ = 166100400. Its totient is φ = 165712404.

The previous prime is 165906379. The next prime is 165906431. The reversal of 165906401 is 104609561.

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 165906401 - 2¹⁸ = 165644257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165906431) 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, 95711 + ... + 97428.

It is an arithmetic number, because the mean of its divisors is an integer number (41525100).

Almost surely, 2^165906401 is an apocalyptic number.

It is an amenable number.

165906401 is a deficient number, since it is larger than the sum of its proper divisors (193999).

165906401 is an equidigital number, since it uses as much as digits as its factorization.

165906401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 193998.

The product of its (nonzero) digits is 6480, while the sum is 32.

The square root of 165906401 is about 12880.4658689040. The cubic root of 165906401 is about 549.4831519233.

The spelling of 165906401 in words is "one hundred sixty-five million, nine hundred six thousand, four hundred one".