138533021 has 6 divisors (see below), whose sum is σ = 152271966. Its totient is φ = 125939000.

The previous prime is 138533011. The next prime is 138533053. The reversal of 138533021 is 120335831.

It can be written as a sum of positive squares in only one way, i.e., 138532900 + 121 = 11770^2 + 11^2 .

It is not a de Polignac number, because 138533021 - 2⁶ = 138532957 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138533011) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 572330 + ... + 572571.

It is an arithmetic number, because the mean of its divisors is an integer number (25378661).

Almost surely, 2^138533021 is an apocalyptic number.

138533021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

138533021 is a deficient number, since it is larger than the sum of its proper divisors (13738945).

138533021 is a wasteful number, since it uses less digits than its factorization.

138533021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1144923 (or 1144912 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 138533021 is about 11770.0051401858. The cubic root of 138533021 is about 517.4294003124.

Adding to 138533021 its reverse (120335831), we get a palindrome (258868852).

The spelling of 138533021 in words is "one hundred thirty-eight million, five hundred thirty-three thousand, twenty-one".