139968581 has 2 divisors, whose sum is σ = 139968582. Its totient is φ = 139968580.

The previous prime is 139968571. The next prime is 139968617. The reversal of 139968581 is 185869931.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 139027681 + 940900 = 11791^2 + 970^2 .

It is a cyclic number.

It is not a de Polignac number, because 139968581 - 2²² = 135774277 is a prime.

It is a super-2 number, since 2×139968581² = 39182407334307122, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (139968511) 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 as a sum of consecutive naturals, namely, 69984290 + 69984291.

It is an arithmetic number, because the mean of its divisors is an integer number (69984291).

Almost surely, 2^139968581 is an apocalyptic number.

It is an amenable number.

139968581 is a deficient number, since it is larger than the sum of its proper divisors (1).

139968581 is an equidigital number, since it uses as much as digits as its factorization.

139968581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 466560, while the sum is 50.

The square root of 139968581 is about 11830.8317966236. The cubic root of 139968581 is about 519.2105637142.

The spelling of 139968581 in words is "one hundred thirty-nine million, nine hundred sixty-eight thousand, five hundred eighty-one".