138821818 has 8 divisors (see below), whose sum is σ = 213311700. Its totient is φ = 67717920.

The previous prime is 138821783. The next prime is 138821831. The reversal of 138821818 is 818128831.

138821818 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 119311929 + 19509889 = 10923^2 + 4417^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 846393 + ... + 846556.

Almost surely, 2^138821818 is an apocalyptic number.

138821818 is a deficient number, since it is larger than the sum of its proper divisors (74489882).

138821818 is a wasteful number, since it uses less digits than its factorization.

138821818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1692992.

The product of its digits is 24576, while the sum is 40.

The square root of 138821818 is about 11782.2670993319. The cubic root of 138821818 is about 517.7887089648.

The spelling of 138821818 in words is "one hundred thirty-eight million, eight hundred twenty-one thousand, eight hundred eighteen".