28128881631 has 4 divisors (see below), whose sum is σ = 37505175512. Its totient is φ = 18752587752.

The previous prime is 28128881609. The next prime is 28128881653. The reversal of 28128881631 is 13618882182.

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

It is an interprime number because it is at equal distance from previous prime (28128881609) and next prime (28128881653).

It is not a de Polignac number, because 28128881631 - 2⁹ = 28128881119 is a prime.

It is a super-2 number, since 2×28128881631² (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 (28128883631) 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, 4688146936 + ... + 4688146941.

It is an arithmetic number, because the mean of its divisors is an integer number (9376293878).

Almost surely, 2^28128881631 is an apocalyptic number.

28128881631 is a deficient number, since it is larger than the sum of its proper divisors (9376293881).

28128881631 is an equidigital number, since it uses as much as digits as its factorization.

28128881631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9376293880.

The product of its digits is 294912, while the sum is 48.

The spelling of 28128881631 in words is "twenty-eight billion, one hundred twenty-eight million, eight hundred eighty-one thousand, six hundred thirty-one".