138782521 has 2 divisors, whose sum is σ = 138782522. Its totient is φ = 138782520.

The previous prime is 138782477. The next prime is 138782533. The reversal of 138782521 is 125287831.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 99281296 + 39501225 = 9964^2 + 6285^2 .

It is a cyclic number.

It is not a de Polignac number, because 138782521 - 2¹⁵ = 138749753 is a prime.

It is equal to p_7847155 and since 138782521 and 7847155 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (138782551) by changing a digit.

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 as a sum of consecutive naturals, namely, 69391260 + 69391261.

It is an arithmetic number, because the mean of its divisors is an integer number (69391261).

Almost surely, 2^138782521 is an apocalyptic number.

It is an amenable number.

138782521 is a deficient number, since it is larger than the sum of its proper divisors (1).

138782521 is an equidigital number, since it uses as much as digits as its factorization.

138782521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 26880, while the sum is 37.

The square root of 138782521 is about 11780.5993480807. The cubic root of 138782521 is about 517.7398466571.

The spelling of 138782521 in words is "one hundred thirty-eight million, seven hundred eighty-two thousand, five hundred twenty-one".