138032281 has 8 divisors (see below), whose sum is σ = 141589224. Its totient is φ = 134484480.

The previous prime is 138032273. The next prime is 138032287. The reversal of 138032281 is 182230831.

It can be written as a sum of positive squares in 4 ways, for example, as 9096256 + 128936025 = 3016^2 + 11355^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 138032281 - 2³ = 138032273 is a prime.

It is a super-2 number, since 2×138032281² = 38105821196125922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138032287) 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, 36621 + ... + 40213.

It is an arithmetic number, because the mean of its divisors is an integer number (17698653).

Almost surely, 2^138032281 is an apocalyptic number.

It is an amenable number.

138032281 is a deficient number, since it is larger than the sum of its proper divisors (3556943).

138032281 is an equidigital number, since it uses as much as digits as its factorization.

138032281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4571.

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 138032281 is about 11748.7140147337. The cubic root of 138032281 is about 516.8052160286.

The spelling of 138032281 in words is "one hundred thirty-eight million, thirty-two thousand, two hundred eighty-one".