12649728778 has 4 divisors (see below), whose sum is σ = 18974593170. Its totient is φ = 6324864388.

The previous prime is 12649728769. The next prime is 12649728779. The reversal of 12649728778 is 87782794621.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 87782794621 = 421 ⋅208510201.

It can be written as a sum of positive squares in only one way, i.e., 12529891969 + 119836809 = 111937^2 + 10947^2 .

It is a super-2 number, since 2×12649728778² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (12649728779) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3162432193 + ... + 3162432196.

Almost surely, 2^12649728778 is an apocalyptic number.

12649728778 is a deficient number, since it is larger than the sum of its proper divisors (6324864392).

12649728778 is an equidigital number, since it uses as much as digits as its factorization.

12649728778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6324864391.

The product of its digits is 18966528, while the sum is 61.

The spelling of 12649728778 in words is "twelve billion, six hundred forty-nine million, seven hundred twenty-eight thousand, seven hundred seventy-eight".