138155399 has 4 divisors (see below), whose sum is σ = 138179664. Its totient is φ = 138131136.

The previous prime is 138155393. The next prime is 138155401. The reversal of 138155399 is 993551831.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 993551831 = 313 ⋅3174287.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-138155399 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 (138155393) 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, 1559 + ... + 16695.

It is an arithmetic number, because the mean of its divisors is an integer number (34544916).

Almost surely, 2^138155399 is an apocalyptic number.

138155399 is a deficient number, since it is larger than the sum of its proper divisors (24265).

138155399 is an equidigital number, since it uses as much as digits as its factorization.

138155399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24264.

The product of its digits is 145800, while the sum is 44.

The square root of 138155399 is about 11753.9524841646. The cubic root of 138155399 is about 516.9588253047.

The spelling of 138155399 in words is "one hundred thirty-eight million, one hundred fifty-five thousand, three hundred ninety-nine".