12638784661 has 12 divisors (see below), whose sum is σ = 13093598700. Its totient is φ = 12199278720.

The previous prime is 12638784649. The next prime is 12638784673. The reversal of 12638784661 is 16648783621.

It is an interprime number because it is at equal distance from previous prime (12638784649) and next prime (12638784673).

It can be written as a sum of positive squares in 2 ways, for example, as 4969404036 + 7669380625 = 70494^2 + 87575^2 .

It is not a de Polignac number, because 12638784661 - 2⁹ = 12638784149 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 12638784599 and 12638784608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12638584661) 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, 356925 + ... + 390733.

It is an arithmetic number, because the mean of its divisors is an integer number (1091133225).

Almost surely, 2^12638784661 is an apocalyptic number.

It is an amenable number.

12638784661 is a deficient number, since it is larger than the sum of its proper divisors (454814039).

12638784661 is an equidigital number, since it uses as much as digits as its factorization.

12638784661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34260 (or 34229 counting only the distinct ones).

The product of its digits is 2322432, while the sum is 52.

The spelling of 12638784661 in words is "twelve billion, six hundred thirty-eight million, seven hundred eighty-four thousand, six hundred sixty-one".