26643006661 has 4 divisors (see below), whose sum is σ = 27079777324. Its totient is φ = 26206236000.

The previous prime is 26643006623. The next prime is 26643006683. The reversal of 26643006661 is 16660034662.

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 1268428225 + 25374578436 = 35615^2 + 159294^2 .

It is a cyclic number.

It is not a de Polignac number, because 26643006661 - 2¹⁵ = 26642973893 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (26643006161) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 218385240 + ... + 218385361.

It is an arithmetic number, because the mean of its divisors is an integer number (6769944331).

Almost surely, 2^26643006661 is an apocalyptic number.

It is an amenable number.

26643006661 is a deficient number, since it is larger than the sum of its proper divisors (436770663).

26643006661 is an equidigital number, since it uses as much as digits as its factorization.

26643006661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 436770662.

The product of its (nonzero) digits is 186624, while the sum is 40.

The spelling of 26643006661 in words is "twenty-six billion, six hundred forty-three million, six thousand, six hundred sixty-one".