165420321 has 16 divisors (see below), whose sum is σ = 248909760. Its totient is φ = 96797120.

The previous prime is 165420293. The next prime is 165420331. The reversal of 165420321 is 123024561.

It is a cyclic number.

It is not a de Polignac number, because 165420321 - 2¹⁸ = 165158177 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 165420291 and 165420300.

It is not an unprimeable number, because it can be changed into a prime (165420331) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 85470 + ... + 87383.

It is an arithmetic number, because the mean of its divisors is an integer number (15556860).

Almost surely, 2^165420321 is an apocalyptic number.

165420321 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

165420321 is a deficient number, since it is larger than the sum of its proper divisors (83489439).

165420321 is a wasteful number, since it uses less digits than its factorization.

165420321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 172896.

The product of its (nonzero) digits is 1440, while the sum is 24.

The square root of 165420321 is about 12861.5831451653. The cubic root of 165420321 is about 548.9459935395.

Adding to 165420321 its reverse (123024561), we get a palindrome (288444882).

The spelling of 165420321 in words is "one hundred sixty-five million, four hundred twenty thousand, three hundred twenty-one".