165221823551 has 4 divisors (see below), whose sum is σ = 166330695000. Its totient is φ = 164112952104.

The previous prime is 165221823521. The next prime is 165221823577. The reversal of 165221823551 is 155328122561.

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

It is a cyclic number.

It is not a de Polignac number, because 165221823551 - 2¹⁰ = 165221822527 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 165221823499 and 165221823508.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165221823521) 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, 554435501 + ... + 554435798.

It is an arithmetic number, because the mean of its divisors is an integer number (41582673750).

Almost surely, 2^165221823551 is an apocalyptic number.

165221823551 is a deficient number, since it is larger than the sum of its proper divisors (1108871449).

165221823551 is a wasteful number, since it uses less digits than its factorization.

165221823551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1108871448.

The product of its digits is 144000, while the sum is 41.

The spelling of 165221823551 in words is "one hundred sixty-five billion, two hundred twenty-one million, eight hundred twenty-three thousand, five hundred fifty-one".