138721225 has 18 divisors (see below), whose sum is σ = 176166366. Its totient is φ = 108360000.

The previous prime is 138721217. The next prime is 138721237. The reversal of 138721225 is 522127831.

It can be written as a sum of positive squares in 3 ways, for example, as 9853321 + 128867904 = 3139^2 + 11352^2 .

It is not a de Polignac number, because 138721225 - 2³ = 138721217 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 44725 + ... + 47725.

Almost surely, 2^138721225 is an apocalyptic number.

It is an amenable number.

138721225 is a deficient number, since it is larger than the sum of its proper divisors (37445141).

138721225 is an equidigital number, since it uses as much as digits as its factorization.

138721225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3097 (or 3049 counting only the distinct ones).

The product of its digits is 6720, while the sum is 31.

The square root of 138721225 is about 11777.9974953300. The cubic root of 138721225 is about 517.6636121411.

The spelling of 138721225 in words is "one hundred thirty-eight million, seven hundred twenty-one thousand, two hundred twenty-five".