165021056209 has 4 divisors (see below), whose sum is σ = 166225589604. Its totient is φ = 163816522816.

The previous prime is 165021056159. The next prime is 165021056243. The reversal of 165021056209 is 902650120561.

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 143508380625 + 21512675584 = 378825^2 + 146672^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-165021056209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165021056509) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 602266492 + ... + 602266765.

It is an arithmetic number, because the mean of its divisors is an integer number (41556397401).

Almost surely, 2^165021056209 is an apocalyptic number.

It is an amenable number.

165021056209 is a deficient number, since it is larger than the sum of its proper divisors (1204533395).

165021056209 is a wasteful number, since it uses less digits than its factorization.

165021056209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1204533394.

The product of its (nonzero) digits is 32400, while the sum is 37.

The spelling of 165021056209 in words is "one hundred sixty-five billion, twenty-one million, fifty-six thousand, two hundred nine".