12928781 has 4 divisors (see below), whose sum is σ = 12936000. Its totient is φ = 12921564.

The previous prime is 12928757. The next prime is 12928813. The reversal of 12928781 is 18782921.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 12928781 - 2⁶ = 12928717 is a prime.

It is a super-2 number, since 2×12928781² = 334306756291922, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12928711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1340 + ... + 5258.

It is an arithmetic number, because the mean of its divisors is an integer number (3234000).

Almost surely, 2^12928781 is an apocalyptic number.

It is an amenable number.

12928781 is a deficient number, since it is larger than the sum of its proper divisors (7219).

12928781 is an equidigital number, since it uses as much as digits as its factorization.

12928781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7218.

The product of its digits is 16128, while the sum is 38.

The square root of 12928781 is about 3595.6614134259. The cubic root of 12928781 is about 234.7032984076.

The spelling of 12928781 in words is "twelve million, nine hundred twenty-eight thousand, seven hundred eighty-one".