665131012581 has 16 divisors (see below), whose sum is σ = 1066876812800. Its totient is φ = 360070923888.

The previous prime is 665131012549. The next prime is 665131012583. The reversal of 665131012581 is 185210131566.

It is a happy number.

It is not a de Polignac number, because 665131012581 - 2⁵ = 665131012549 is a prime.

It is a super-2 number, since 2×665131012581² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665131012583) 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 15 ways as a sum of consecutive naturals, for example, 833497111 + ... + 833497908.

It is an arithmetic number, because the mean of its divisors is an integer number (66679800800).

Almost surely, 2^665131012581 is an apocalyptic number.

It is an amenable number.

665131012581 is a deficient number, since it is larger than the sum of its proper divisors (401745800219).

665131012581 is a wasteful number, since it uses less digits than its factorization.

665131012581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1666995048.

The product of its (nonzero) digits is 43200, while the sum is 39.

The spelling of 665131012581 in words is "six hundred sixty-five billion, one hundred thirty-one million, twelve thousand, five hundred eighty-one".