28731997765 has 4 divisors (see below), whose sum is σ = 34478397324. Its totient is φ = 22985598208.

The previous prime is 28731997741. The next prime is 28731997769. The reversal of 28731997765 is 56779913782.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 13844581569 + 14887416196 = 117663^2 + 122014^2 .

It is a cyclic number.

It is not a de Polignac number, because 28731997765 - 2³³ = 20142063173 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 28731997697 and 28731997706.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28731997769) 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 3 ways as a sum of consecutive naturals, for example, 2873199772 + ... + 2873199781.

It is an arithmetic number, because the mean of its divisors is an integer number (8619599331).

Almost surely, 2^28731997765 is an apocalyptic number.

It is an amenable number.

28731997765 is a deficient number, since it is larger than the sum of its proper divisors (5746399559).

28731997765 is an equidigital number, since it uses as much as digits as its factorization.

28731997765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5746399558.

The product of its digits is 40007520, while the sum is 64.

The spelling of 28731997765 in words is "twenty-eight billion, seven hundred thirty-one million, nine hundred ninety-seven thousand, seven hundred sixty-five".