138243555 has 24 divisors (see below), whose sum is σ = 242515728. Its totient is φ = 72839616.

The previous prime is 138243517. The next prime is 138243569. The reversal of 138243555 is 555342831.

It is not a de Polignac number, because 138243555 - 2⁶ = 138243491 is a prime.

It is a super-2 number, since 2×138243555² = 38222560998076050, which contains 22 as substring.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 14772 + ... + 22241.

It is an arithmetic number, because the mean of its divisors is an integer number (10104822).

Almost surely, 2^138243555 is an apocalyptic number.

138243555 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

138243555 is a deficient number, since it is larger than the sum of its proper divisors (104272173).

138243555 is a wasteful number, since it uses less digits than its factorization.

138243555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37107 (or 37104 counting only the distinct ones).

The product of its digits is 72000, while the sum is 36.

The square root of 138243555 is about 11757.7019438324. The cubic root of 138243555 is about 517.0687578702.

The spelling of 138243555 in words is "one hundred thirty-eight million, two hundred forty-three thousand, five hundred fifty-five".