6641568581605 has 4 divisors (see below), whose sum is σ = 7969882297932. Its totient is φ = 5313254865280.

The previous prime is 6641568581567. The next prime is 6641568581611. The reversal of 6641568581605 is 5061858651466.

It is a happy number.

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 4831529309476 + 1810039272129 = 2198074^2 + 1345377^2 .

It is a de Polignac number, because none of the positive numbers 2^k-6641568581605 is a prime.

It is a super-2 number, since 2×6641568581605² (a number of 26 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 664156858156 + ... + 664156858165.

It is an arithmetic number, because the mean of its divisors is an integer number (1992470574483).

Almost surely, 2^{6641568581605} is an apocalyptic number.

It is an amenable number.

6641568581605 is a deficient number, since it is larger than the sum of its proper divisors (1328313716327).

6641568581605 is a wasteful number, since it uses less digits than its factorization.

6641568581605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1328313716326.

The product of its (nonzero) digits is 41472000, while the sum is 61.

The spelling of 6641568581605 in words is "six trillion, six hundred forty-one billion, five hundred sixty-eight million, five hundred eighty-one thousand, six hundred five".