1605506506081 has 4 divisors (see below), whose sum is σ = 1605550537492. Its totient is φ = 1605462474672.

The previous prime is 1605506506069. The next prime is 1605506506133. The reversal of 1605506506081 is 1806056055061.

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 45403086400 + 1560103419681 = 213080^2 + 1249041^2 .

It is a cyclic number.

It is not a de Polignac number, because 1605506506081 - 2¹¹ = 1605506504033 is a prime.

It is a super-2 number, since 2×1605506506081² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1605506506181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21960966 + ... + 22033951.

It is an arithmetic number, because the mean of its divisors is an integer number (401387634373).

Almost surely, 2^{1605506506081} is an apocalyptic number.

It is an amenable number.

1605506506081 is a deficient number, since it is larger than the sum of its proper divisors (44031411).

1605506506081 is an equidigital number, since it uses as much as digits as its factorization.

1605506506081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44031410.

The product of its (nonzero) digits is 216000, while the sum is 43.

The spelling of 1605506506081 in words is "one trillion, six hundred five billion, five hundred six million, five hundred six thousand, eighty-one".