28778351831 has 4 divisors (see below), whose sum is σ = 28818942600. Its totient is φ = 28737761064.

The previous prime is 28778351827. The next prime is 28778351837. The reversal of 28778351831 is 13815387782.

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

It is a cyclic number.

It is not a de Polignac number, because 28778351831 - 2² = 28778351827 is a prime.

It is a super-2 number, since 2×28778351831² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28778351837) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20294321 + ... + 20295738.

It is an arithmetic number, because the mean of its divisors is an integer number (7204735650).

Almost surely, 2^28778351831 is an apocalyptic number.

28778351831 is a deficient number, since it is larger than the sum of its proper divisors (40590769).

28778351831 is an equidigital number, since it uses as much as digits as its factorization.

28778351831 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40590768.

The product of its digits is 2257920, while the sum is 53.

The spelling of 28778351831 in words is "twenty-eight billion, seven hundred seventy-eight million, three hundred fifty-one thousand, eight hundred thirty-one".