138871987 has 2 divisors, whose sum is σ = 138871988. Its totient is φ = 138871986.

The previous prime is 138871973. The next prime is 138871991. The reversal of 138871987 is 789178831.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-138871987 is a prime.

It is not a weakly prime, because it can be changed into another prime (138871927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69435993 + 69435994.

It is an arithmetic number, because the mean of its divisors is an integer number (69435994).

Almost surely, 2^138871987 is an apocalyptic number.

138871987 is a deficient number, since it is larger than the sum of its proper divisors (1).

138871987 is an equidigital number, since it uses as much as digits as its factorization.

138871987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 677376, while the sum is 52.

The square root of 138871987 is about 11784.3959115434. The cubic root of 138871987 is about 517.8510762340.

The spelling of 138871987 in words is "one hundred thirty-eight million, eight hundred seventy-one thousand, nine hundred eighty-seven".