165417452021 has 4 divisors (see below), whose sum is σ = 165441222444. Its totient is φ = 165393681600.

The previous prime is 165417451981. The next prime is 165417452033. The reversal of 165417452021 is 120254714561.

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

It can be written as a sum of positive squares in 2 ways, for example, as 134021155921 + 31396296100 = 366089^2 + 177190^2 .

It is a cyclic number.

It is not a de Polignac number, because 165417452021 - 2¹⁰ = 165417450997 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 (165417452521) by changing a digit.

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 in 3 ways as a sum of consecutive naturals, for example, 11874770 + ... + 11888691.

It is an arithmetic number, because the mean of its divisors is an integer number (41360305611).

Almost surely, 2^165417452021 is an apocalyptic number.

It is an amenable number.

165417452021 is a deficient number, since it is larger than the sum of its proper divisors (23770423).

165417452021 is an equidigital number, since it uses as much as digits as its factorization.

165417452021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23770422.

The product of its (nonzero) digits is 67200, while the sum is 38.

The spelling of 165417452021 in words is "one hundred sixty-five billion, four hundred seventeen million, four hundred fifty-two thousand, twenty-one".