12781781326556 has 24 divisors (see below), whose sum is σ = 24801608480880. Its totient is φ = 5714656329600.

The previous prime is 12781781326463. The next prime is 12781781326591. The reversal of 12781781326556 is 65562318718721.

It is a happy number.

It is a super-2 number, since 2×12781781326556² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2381104121 + ... + 2381109488.

It is an arithmetic number, because the mean of its divisors is an integer number (1033400353370).

Almost surely, 2^{12781781326556} is an apocalyptic number.

It is an amenable number.

12781781326556 is a deficient number, since it is larger than the sum of its proper divisors (12019827154324).

12781781326556 is a wasteful number, since it uses less digits than its factorization.

12781781326556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4762213685 (or 4762213683 counting only the distinct ones).

The product of its digits is 33868800, while the sum is 62.

The spelling of 12781781326556 in words is "twelve trillion, seven hundred eighty-one billion, seven hundred eighty-one million, three hundred twenty-six thousand, five hundred fifty-six".