138688777 has 2 divisors, whose sum is σ = 138688778. Its totient is φ = 138688776.

The previous prime is 138688769. The next prime is 138688787. The reversal of 138688777 is 777886831.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 98188281 + 40500496 = 9909^2 + 6364^2 .

It is a cyclic number.

It is not a de Polignac number, because 138688777 - 2³ = 138688769 is a prime.

It is not a weakly prime, because it can be changed into another prime (138688787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69344388 + 69344389.

It is an arithmetic number, because the mean of its divisors is an integer number (69344389).

Almost surely, 2^138688777 is an apocalyptic number.

It is an amenable number.

138688777 is a deficient number, since it is larger than the sum of its proper divisors (1).

138688777 is an equidigital number, since it uses as much as digits as its factorization.

138688777 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3161088, while the sum is 55.

The square root of 138688777 is about 11776.6199310328. The cubic root of 138688777 is about 517.6232471123.

The spelling of 138688777 in words is "one hundred thirty-eight million, six hundred eighty-eight thousand, seven hundred seventy-seven".