138509361 has 9 divisors (see below), whose sum is σ = 200120089. Its totient is φ = 92316036.

The previous prime is 138509347. The next prime is 138509369. The reversal of 138509361 is 163905831.

It is a happy number.

The square root of 138509361 is 11769.

It is a perfect power (a square), and thus also a powerful number.

It is a tau number, because it is divible by the number of its divisors (9).

It is a de Polignac number, because none of the positive numbers 2^k-138509361 is a prime.

It is a super-4 number, since 4×138509361⁴ (a number of 34 digits) contains 4444 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138509369) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 33346 + ... + 37268.

Almost surely, 2^138509361 is an apocalyptic number.

138509361 is the 11769-th square number.

138509361 is the 5885-th centered octagonal number.

It is an amenable number.

138509361 is a deficient number, since it is larger than the sum of its proper divisors (61610728).

138509361 is an frugal number, since it uses more digits than its factorization.

138509361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7852 (or 3926 counting only the distinct ones).

The product of its (nonzero) digits is 19440, while the sum is 36.

The cubic root of 138509361 is about 517.3999414475.

Multiplying 138509361 by its sum of digits (36), we get a square (4986336996 = 70614²).

The spelling of 138509361 in words is "one hundred thirty-eight million, five hundred nine thousand, three hundred sixty-one".