138278387 has 4 divisors (see below), whose sum is σ = 148915200. Its totient is φ = 127641576.

The previous prime is 138278377. The next prime is 138278417. The reversal of 138278387 is 783872831.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 783872831 = 7 ⋅111981833.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-138278387 is a prime.

It is a super-2 number, since 2×138278387² = 38241824622643538, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138278377) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5318387 + ... + 5318412.

It is an arithmetic number, because the mean of its divisors is an integer number (37228800).

Almost surely, 2^138278387 is an apocalyptic number.

138278387 is a deficient number, since it is larger than the sum of its proper divisors (10636813).

138278387 is a wasteful number, since it uses less digits than its factorization.

138278387 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10636812.

The product of its digits is 451584, while the sum is 47.

The square root of 138278387 is about 11759.1830923751. The cubic root of 138278387 is about 517.1121812967.

The spelling of 138278387 in words is "one hundred thirty-eight million, two hundred seventy-eight thousand, three hundred eighty-seven".