138233021 has 8 divisors (see below), whose sum is σ = 139174200. Its totient is φ = 137295360.

The previous prime is 138233009. The next prime is 138233033. The reversal of 138233021 is 120332831.

138233021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (138233009) and next prime (138233033).

It can be written as a sum of positive squares in 4 ways, for example, as 35940025 + 102292996 = 5995^2 + 10114^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-138233021 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 (138233321) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 170465 + ... + 171273.

It is an arithmetic number, because the mean of its divisors is an integer number (17396775).

Almost surely, 2^138233021 is an apocalyptic number.

It is an amenable number.

138233021 is a deficient number, since it is larger than the sum of its proper divisors (941179).

138233021 is an equidigital number, since it uses as much as digits as its factorization.

138233021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1759.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 138233021 is about 11757.2539736114. The cubic root of 138233021 is about 517.0556241882.

Adding to 138233021 its reverse (120332831), we get a palindrome (258565852).

The spelling of 138233021 in words is "one hundred thirty-eight million, two hundred thirty-three thousand, twenty-one".