28378434681 has 27 divisors (see below), whose sum is σ = 41339284077. Its totient is φ = 18759594240.

The previous prime is 28378434647. The next prime is 28378434727. The reversal of 28378434681 is 18643487382.

The square root of 28378434681 is 168459.

It is a perfect power (a square), and thus also a powerful number.

28378434681 is a `hidden beast` number, since 2 + 83 + 78 + 434 + 68 + 1 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 81812025 + 28296622656 = 9045^2 + 168216^2 .

It is not a de Polignac number, because 28378434681 - 2¹⁵ = 28378401913 is a prime.

It is a super-2 number, since 2×28378434681² (a number of 22 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (28378434631) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 117752721 + ... + 117752961.

Almost surely, 2^28378434681 is an apocalyptic number.

28378434681 is the 168459-th square number.

28378434681 is the 84230-th centered octagonal number.

It is an amenable number.

28378434681 is a deficient number, since it is larger than the sum of its proper divisors (12960849396).

28378434681 is an frugal number, since it uses more digits than its factorization.

28378434681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 954 (or 477 counting only the distinct ones).

The product of its digits is 6193152, while the sum is 54.

The spelling of 28378434681 in words is "twenty-eight billion, three hundred seventy-eight million, four hundred thirty-four thousand, six hundred eighty-one".