165505951 has 4 divisors (see below), whose sum is σ = 178237192. Its totient is φ = 152774712.

The previous prime is 165505943. The next prime is 165505957. The reversal of 165505951 is 159505561.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 159505561 = 379 ⋅420859.

It is a cyclic number.

It is not a de Polignac number, because 165505951 - 2³ = 165505943 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 165505951.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165505957) 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, 6365601 + ... + 6365626.

It is an arithmetic number, because the mean of its divisors is an integer number (44559298).

Almost surely, 2^165505951 is an apocalyptic number.

165505951 is a deficient number, since it is larger than the sum of its proper divisors (12731241).

165505951 is a wasteful number, since it uses less digits than its factorization.

165505951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12731240.

The product of its (nonzero) digits is 33750, while the sum is 37.

The square root of 165505951 is about 12864.9116203727. The cubic root of 165505951 is about 549.0406980202.

The spelling of 165505951 in words is "one hundred sixty-five million, five hundred five thousand, nine hundred fifty-one".