165515810381 has 2 divisors, whose sum is σ = 165515810382. Its totient is φ = 165515810380.

The previous prime is 165515810351. The next prime is 165515810479. The reversal of 165515810381 is 183018515561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 126071864356 + 39443946025 = 355066^2 + 198605^2 .

It is a cyclic number.

It is not a de Polignac number, because 165515810381 - 2¹⁰ = 165515809357 is a prime.

It is a super-2 number, since 2×165515810381² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (165515810311) 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 as a sum of consecutive naturals, namely, 82757905190 + 82757905191.

It is an arithmetic number, because the mean of its divisors is an integer number (82757905191).

Almost surely, 2^165515810381 is an apocalyptic number.

It is an amenable number.

165515810381 is a deficient number, since it is larger than the sum of its proper divisors (1).

165515810381 is an equidigital number, since it uses as much as digits as its factorization.

165515810381 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144000, while the sum is 44.

The spelling of 165515810381 in words is "one hundred sixty-five billion, five hundred fifteen million, eight hundred ten thousand, three hundred eighty-one".