138821868 has 36 divisors (see below), whose sum is σ = 352185288. Its totient is φ = 46105920.

The previous prime is 138821849. The next prime is 138821873. The reversal of 138821868 is 868128831.

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×138821868² = 38543022070018848, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3255 + ... + 16977.

Almost surely, 2^138821868 is an apocalyptic number.

138821868 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

138821868 is an abundant number, since it is smaller than the sum of its proper divisors (213363420).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

138821868 is a wasteful number, since it uses less digits than its factorization.

138821868 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14014 (or 14009 counting only the distinct ones).

The product of its digits is 147456, while the sum is 45.

The square root of 138821868 is about 11782.2692211645. The cubic root of 138821868 is about 517.7887711295.

The spelling of 138821868 in words is "one hundred thirty-eight million, eight hundred twenty-one thousand, eight hundred sixty-eight".