138509551 has 2 divisors, whose sum is σ = 138509552. Its totient is φ = 138509550.

The previous prime is 138509549. The next prime is 138509573. The reversal of 138509551 is 155905831.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 138509551 - 2¹ = 138509549 is a prime.

Together with 138509549, it forms a pair of twin primes.

It is equal to p_7832566 and since 138509551 and 7832566 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 138509551.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138509851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69254775 + 69254776.

It is an arithmetic number, because the mean of its divisors is an integer number (69254776).

Almost surely, 2^138509551 is an apocalyptic number.

138509551 is a deficient number, since it is larger than the sum of its proper divisors (1).

138509551 is an equidigital number, since it uses as much as digits as its factorization.

138509551 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 27000, while the sum is 37.

The square root of 138509551 is about 11769.0080720509. The cubic root of 138509551 is about 517.4001780282.

The spelling of 138509551 in words is "one hundred thirty-eight million, five hundred nine thousand, five hundred fifty-one".