1640504995685 has 4 divisors (see below), whose sum is σ = 1968605994828. Its totient is φ = 1312403996544.

The previous prime is 1640504995673. The next prime is 1640504995693. The reversal of 1640504995685 is 5865994050461.

It is a Cunningham number, because it is equal to 1280822²+1.

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 590583028036 + 1049921967649 = 768494^2 + 1024657^2 .

It is a cyclic number.

It is not a de Polignac number, because 1640504995685 - 2⁴ = 1640504995669 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 164050499564 + ... + 164050499573.

It is an arithmetic number, because the mean of its divisors is an integer number (492151498707).

Almost surely, 2^{1640504995685} is an apocalyptic number.

It is an amenable number.

1640504995685 is a deficient number, since it is larger than the sum of its proper divisors (328100999143).

1640504995685 is an equidigital number, since it uses as much as digits as its factorization.

1640504995685 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 328100999142.

The product of its (nonzero) digits is 46656000, while the sum is 62.

The spelling of 1640504995685 in words is "one trillion, six hundred forty billion, five hundred four million, nine hundred ninety-five thousand, six hundred eighty-five".