28131612381 has 6 divisors (see below), whose sum is σ = 40634551230. Its totient is φ = 18754408248.

The previous prime is 28131612343. The next prime is 28131612389. The reversal of 28131612381 is 18321613182.

28131612381 is a `hidden beast` number, since 2 + 8 + 1 + 3 + 1 + 612 + 38 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 15354927225 + 12776685156 = 123915^2 + 113034^2 .

It is not a de Polignac number, because 28131612381 - 2¹¹ = 28131610333 is a prime.

It is a super-2 number, since 2×28131612381² (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 (28131612389) 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 5 ways as a sum of consecutive naturals, for example, 1562867346 + ... + 1562867363.

It is an arithmetic number, because the mean of its divisors is an integer number (6772425205).

Almost surely, 2^28131612381 is an apocalyptic number.

It is an amenable number.

28131612381 is a deficient number, since it is larger than the sum of its proper divisors (12502938849).

28131612381 is a wasteful number, since it uses less digits than its factorization.

28131612381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3125734715 (or 3125734712 counting only the distinct ones).

The product of its digits is 13824, while the sum is 36.

The spelling of 28131612381 in words is "twenty-eight billion, one hundred thirty-one million, six hundred twelve thousand, three hundred eighty-one".