2661356564128 has 72 divisors (see below), whose sum is σ = 5530926319380. Its totient is φ = 1260391587840.

The previous prime is 2661356564107. The next prime is 2661356564129. The reversal of 2661356564128 is 8214656531662.

It is a happy number.

2661356564128 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 2353806460944 + 307550103184 = 1534212^2 + 554572^2 .

It is a super-2 number, since 2×2661356564128² (a number of 26 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (2661356564129) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 66299968 + ... + 66340096.

Almost surely, 2^{2661356564128} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2661356564128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2765463159690).

2661356564128 is an abundant number, since it is smaller than the sum of its proper divisors (2869569755252).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

2661356564128 is a wasteful number, since it uses less digits than its factorization.

2661356564128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45918 (or 45891 counting only the distinct ones).

The product of its digits is 12441600, while the sum is 55.

The spelling of 2661356564128 in words is "two trillion, six hundred sixty-one billion, three hundred fifty-six million, five hundred sixty-four thousand, one hundred twenty-eight".