165400405 has 4 divisors (see below), whose sum is σ = 198480492. Its totient is φ = 132320320.

The previous prime is 165400381. The next prime is 165400447. The reversal of 165400405 is 504004561.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 504004561 = 107 ⋅4710323.

It can be written as a sum of positive squares in 2 ways, for example, as 52041796 + 113358609 = 7214^2 + 10647^2 .

It is not a de Polignac number, because 165400405 - 2¹¹ = 165398357 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 165400405.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16540036 + ... + 16540045.

It is an arithmetic number, because the mean of its divisors is an integer number (49620123).

Almost surely, 2^165400405 is an apocalyptic number.

It is an amenable number.

165400405 is a deficient number, since it is larger than the sum of its proper divisors (33080087).

165400405 is an equidigital number, since it uses as much as digits as its factorization.

165400405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33080086.

The product of its (nonzero) digits is 2400, while the sum is 25.

The square root of 165400405 is about 12860.8088781383. The cubic root of 165400405 is about 548.9239622938.

Adding to 165400405 its reverse (504004561), we get a palindrome (669404966).

The spelling of 165400405 in words is "one hundred sixty-five million, four hundred thousand, four hundred five".