138231997 has 4 divisors (see below), whose sum is σ = 140125660. Its totient is φ = 136338336.

The previous prime is 138231983. The next prime is 138232051. The reversal of 138231997 is 799132831.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 63824121 + 74407876 = 7989^2 + 8626^2 .

It is a cyclic number.

It is not a de Polignac number, because 138231997 - 2¹⁹ = 137707709 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138231937) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 946722 + ... + 946867.

It is an arithmetic number, because the mean of its divisors is an integer number (35031415).

Almost surely, 2^138231997 is an apocalyptic number.

It is an amenable number.

138231997 is a deficient number, since it is larger than the sum of its proper divisors (1893663).

138231997 is an equidigital number, since it uses as much as digits as its factorization.

138231997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1893662.

The product of its digits is 81648, while the sum is 43.

The square root of 138231997 is about 11757.2104259471. The cubic root of 138231997 is about 517.0543474401.

The spelling of 138231997 in words is "one hundred thirty-eight million, two hundred thirty-one thousand, nine hundred ninety-seven".