138243947 has 2 divisors, whose sum is σ = 138243948. Its totient is φ = 138243946.

The previous prime is 138243913. The next prime is 138243997. The reversal of 138243947 is 749342831.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 138243947 - 2¹² = 138239851 is a prime.

It is a super-2 number, since 2×138243947² = 38222777764277618, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (138243997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69121973 + 69121974.

It is an arithmetic number, because the mean of its divisors is an integer number (69121974).

Almost surely, 2^138243947 is an apocalyptic number.

138243947 is a deficient number, since it is larger than the sum of its proper divisors (1).

138243947 is an equidigital number, since it uses as much as digits as its factorization.

138243947 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 145152, while the sum is 41.

The square root of 138243947 is about 11757.7186137448. The cubic root of 138243947 is about 517.0692465989.

It can be divided in two parts, 13824 and 3947, that added together give a palindrome (17771).

The spelling of 138243947 in words is "one hundred thirty-eight million, two hundred forty-three thousand, nine hundred forty-seven".