165540406 has 4 divisors (see below), whose sum is σ = 248310612. Its totient is φ = 82770202.

The previous prime is 165540391. The next prime is 165540437. The reversal of 165540406 is 604045561.

It is a semiprime because it is the product of two primes.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 41385100 + ... + 41385103.

It is an arithmetic number, because the mean of its divisors is an integer number (62077653).

Almost surely, 2^165540406 is an apocalyptic number.

165540406 is a deficient number, since it is larger than the sum of its proper divisors (82770206).

165540406 is an equidigital number, since it uses as much as digits as its factorization.

165540406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82770205.

The product of its (nonzero) digits is 14400, while the sum is 31.

The square root of 165540406 is about 12866.2506582143. The cubic root of 165540406 is about 549.0787951089.

Adding to 165540406 its reverse (604045561), we get a palindrome (769585967).

The spelling of 165540406 in words is "one hundred sixty-five million, five hundred forty thousand, four hundred six".