138973609 has 2 divisors, whose sum is σ = 138973610. Its totient is φ = 138973608.

The previous prime is 138973607. The next prime is 138973621. The reversal of 138973609 is 906379831.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 138768400 + 205209 = 11780^2 + 453^2 .

It is a cyclic number.

It is not a de Polignac number, because 138973609 - 2¹ = 138973607 is a prime.

It is a super-3 number, since 3×138973609³ (a number of 25 digits) contains 333 as substring.

Together with 138973607, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (138973607) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69486804 + 69486805.

It is an arithmetic number, because the mean of its divisors is an integer number (69486805).

Almost surely, 2^138973609 is an apocalyptic number.

It is an amenable number.

138973609 is a deficient number, since it is larger than the sum of its proper divisors (1).

138973609 is an equidigital number, since it uses as much as digits as its factorization.

138973609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 244944, while the sum is 46.

The square root of 138973609 is about 11788.7068417193. The cubic root of 138973609 is about 517.9773609561.

The spelling of 138973609 in words is "one hundred thirty-eight million, nine hundred seventy-three thousand, six hundred nine".