28139525 has 6 divisors (see below), whose sum is σ = 34893042. Its totient is φ = 22511600.

The previous prime is 28139491. The next prime is 28139533. The reversal of 28139525 is 52593182.

It can be written as a sum of positive squares in 3 ways, for example, as 744769 + 27394756 = 863^2 + 5234^2 .

It is not a de Polignac number, because 28139525 - 2⁸ = 28139269 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 562766 + ... + 562815.

It is an arithmetic number, because the mean of its divisors is an integer number (5815507).

Almost surely, 2^28139525 is an apocalyptic number.

28139525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

28139525 is a deficient number, since it is larger than the sum of its proper divisors (6753517).

28139525 is a wasteful number, since it uses less digits than its factorization.

28139525 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1125591 (or 1125586 counting only the distinct ones).

The product of its digits is 21600, while the sum is 35.

The square root of 28139525 is about 5304.6701122690. The cubic root of 28139525 is about 304.1624427595.

The spelling of 28139525 in words is "twenty-eight million, one hundred thirty-nine thousand, five hundred twenty-five".