138361581 has 32 divisors (see below), whose sum is σ = 214704000. Its totient is φ = 87945984.

The previous prime is 138361579. The next prime is 138361621. The reversal of 138361581 is 185163831.

138361581 is a `hidden beast` number, since 1 + 38 + 3 + 615 + 8 + 1 = 666.

It is not a de Polignac number, because 138361581 - 2¹ = 138361579 is a prime.

It is a super-2 number, since 2×138361581² = 38287854193639122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138361541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 63925 + ... + 66053.

It is an arithmetic number, because the mean of its divisors is an integer number (6709500).

Almost surely, 2^138361581 is an apocalyptic number.

It is an amenable number.

138361581 is a deficient number, since it is larger than the sum of its proper divisors (76342419).

138361581 is a wasteful number, since it uses less digits than its factorization.

138361581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2250 (or 2244 counting only the distinct ones).

The product of its digits is 17280, while the sum is 36.

The square root of 138361581 is about 11762.7199660623. The cubic root of 138361581 is about 517.2158658684.

The spelling of 138361581 in words is "one hundred thirty-eight million, three hundred sixty-one thousand, five hundred eighty-one".