165521263 has 4 divisors (see below), whose sum is σ = 169043040. Its totient is φ = 161999488.

The previous prime is 165521261. The next prime is 165521303. The reversal of 165521263 is 362125561.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 362125561 = 7 ⋅51732223.

It is a cyclic number.

It is not a de Polignac number, because 165521263 - 2¹ = 165521261 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165521261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1760818 + ... + 1760911.

It is an arithmetic number, because the mean of its divisors is an integer number (42260760).

Almost surely, 2^165521263 is an apocalyptic number.

165521263 is a deficient number, since it is larger than the sum of its proper divisors (3521777).

165521263 is an equidigital number, since it uses as much as digits as its factorization.

165521263 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3521776.

The product of its digits is 10800, while the sum is 31.

The square root of 165521263 is about 12865.5067136899. The cubic root of 165521263 is about 549.0576292380.

The spelling of 165521263 in words is "one hundred sixty-five million, five hundred twenty-one thousand, two hundred sixty-three".