138897865 has 4 divisors (see below), whose sum is σ = 166677444. Its totient is φ = 111118288.

The previous prime is 138897853. The next prime is 138897883. The reversal of 138897865 is 568798831.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 568798831 = 61 ⋅9324571.

It can be written as a sum of positive squares in 2 ways, for example, as 93954249 + 44943616 = 9693^2 + 6704^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-138897865 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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, 13889782 + ... + 13889791.

It is an arithmetic number, because the mean of its divisors is an integer number (41669361).

Almost surely, 2^138897865 is an apocalyptic number.

It is an amenable number.

138897865 is a deficient number, since it is larger than the sum of its proper divisors (27779579).

138897865 is an equidigital number, since it uses as much as digits as its factorization.

138897865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27779578.

The product of its digits is 2903040, while the sum is 55.

The square root of 138897865 is about 11785.4938377651. The cubic root of 138897865 is about 517.8832404310.

The spelling of 138897865 in words is "one hundred thirty-eight million, eight hundred ninety-seven thousand, eight hundred sixty-five".