28756641781 has 8 divisors (see below), whose sum is σ = 32949221760. Its totient is φ = 24585183888.

The previous prime is 28756641763. The next prime is 28756641811. The reversal of 28756641781 is 18714665782.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28756641781 is a prime.

It is a super-2 number, since 2×28756641781² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28756641731) 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 in 7 ways as a sum of consecutive naturals, for example, 5277601 + ... + 5283046.

It is an arithmetic number, because the mean of its divisors is an integer number (4118652720).

Almost surely, 2^28756641781 is an apocalyptic number.

It is an amenable number.

28756641781 is a deficient number, since it is larger than the sum of its proper divisors (4192579979).

28756641781 is a wasteful number, since it uses less digits than its factorization.

28756641781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10561043.

The product of its digits is 4515840, while the sum is 55.

The spelling of 28756641781 in words is "twenty-eight billion, seven hundred fifty-six million, six hundred forty-one thousand, seven hundred eighty-one".