138867581 has 2 divisors, whose sum is σ = 138867582. Its totient is φ = 138867580.

The previous prime is 138867559. The next prime is 138867593. The reversal of 138867581 is 185768831.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 87516025 + 51351556 = 9355^2 + 7166^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-138867581 is a prime.

It is a super-2 number, since 2×138867581² = 38568410105583122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138861581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69433790 + 69433791.

It is an arithmetic number, because the mean of its divisors is an integer number (69433791).

Almost surely, 2^138867581 is an apocalyptic number.

It is an amenable number.

138867581 is a deficient number, since it is larger than the sum of its proper divisors (1).

138867581 is an equidigital number, since it uses as much as digits as its factorization.

138867581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 322560, while the sum is 47.

The square root of 138867581 is about 11784.2089679367. The cubic root of 138867581 is about 517.8455995452.

The spelling of 138867581 in words is "one hundred thirty-eight million, eight hundred sixty-seven thousand, five hundred eighty-one".