165821045 has 16 divisors (see below), whose sum is σ = 215670000. Its totient is φ = 121665024.

The previous prime is 165821021. The next prime is 165821063. The reversal of 165821045 is 540128561.

It can be written as a sum of positive squares in 8 ways, for example, as 16834609 + 148986436 = 4103^2 + 12206^2 .

It is not a de Polignac number, because 165821045 - 2²⁶ = 98712181 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2081 + ... + 18329.

It is an arithmetic number, because the mean of its divisors is an integer number (13479375).

Almost surely, 2^165821045 is an apocalyptic number.

It is an amenable number.

165821045 is a deficient number, since it is larger than the sum of its proper divisors (49848955).

165821045 is a wasteful number, since it uses less digits than its factorization.

165821045 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16424.

The product of its (nonzero) digits is 9600, while the sum is 32.

The square root of 165821045 is about 12877.1520531521. The cubic root of 165821045 is about 549.3889025367.

The spelling of 165821045 in words is "one hundred sixty-five million, eight hundred twenty-one thousand, forty-five".