1664326511525 has 6 divisors (see below), whose sum is σ = 2063764874322. Its totient is φ = 1331461209200.

The previous prime is 1664326511521. The next prime is 1664326511537. The reversal of 1664326511525 is 5251156234661.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 222902959876 + 1441423551649 = 472126^2 + 1200593^2 .

It is not a de Polignac number, because 1664326511525 - 2² = 1664326511521 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 1664326511525.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1664326511521) 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 5 ways as a sum of consecutive naturals, for example, 33286530206 + ... + 33286530255.

It is an arithmetic number, because the mean of its divisors is an integer number (343960812387).

Almost surely, 2^{1664326511525} is an apocalyptic number.

It is an amenable number.

1664326511525 is a deficient number, since it is larger than the sum of its proper divisors (399438362797).

1664326511525 is an equidigital number, since it uses as much as digits as its factorization.

1664326511525 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66573060471 (or 66573060466 counting only the distinct ones).

The product of its digits is 1296000, while the sum is 47.

The spelling of 1664326511525 in words is "one trillion, six hundred sixty-four billion, three hundred twenty-six million, five hundred eleven thousand, five hundred twenty-five".