28138385025 has 81 divisors (see below), whose sum is σ = 51612443337. Its totient is φ = 14654203200.

The previous prime is 28138384969. The next prime is 28138385029. The reversal of 28138385025 is 52058383182.

The square root of 28138385025 is 167745.

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

28138385025 is a `hidden beast` number, since 2 + 8 + 138 + 3 + 8 + 502 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 211964481 + 27926420544 = 14559^2 + 167112^2 .

It is not a de Polignac number, because 28138385025 - 2²⁷ = 28004167297 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (28138385029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 133357170 + ... + 133357380.

Almost surely, 2^28138385025 is an apocalyptic number.

28138385025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

28138385025 is the 167745-th square number.

28138385025 is the 83873-rd centered octagonal number.

It is an amenable number.

28138385025 is a deficient number, since it is larger than the sum of its proper divisors (23474058312).

28138385025 is an equidigital number, since it uses as much as digits as its factorization.

28138385025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 544 (or 272 counting only the distinct ones).

The product of its (nonzero) digits is 460800, while the sum is 45.

It can be divided in two parts, 2813 and 8385025, that added together give a palindrome (8387838).

The spelling of 28138385025 in words is "twenty-eight billion, one hundred thirty-eight million, three hundred eighty-five thousand, twenty-five".