138997 has 4 divisors (see below), whose sum is σ = 143820. Its totient is φ = 134176.

The previous prime is 138977. The next prime is 139021. The reversal of 138997 is 799831.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 799831 = 31 ⋅25801.

It can be written as a sum of positive squares in 2 ways, for example, as 98596 + 40401 = 314^2 + 201^2 .

It is a cyclic number.

It is not a de Polignac number, because 138997 - 2⁷ = 138869 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 (138917) 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 in 3 ways as a sum of consecutive naturals, for example, 2368 + ... + 2425.

It is an arithmetic number, because the mean of its divisors is an integer number (35955).

2¹³⁸⁹⁹⁷ is an apocalyptic number.

It is an amenable number.

138997 is a deficient number, since it is larger than the sum of its proper divisors (4823).

138997 is an equidigital number, since it uses as much as digits as its factorization.

138997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4822.

The product of its digits is 13608, while the sum is 37.

The square root of 138997 is about 372.8230143111. The cubic root of 138997 is about 51.8006420020.

The spelling of 138997 in words is "one hundred thirty-eight thousand, nine hundred ninety-seven".