139999991 has 2 divisors, whose sum is σ = 139999992. Its totient is φ = 139999990.

The previous prime is 139999973. The next prime is 140000041. The reversal of 139999991 is 199999931.

It is a weak prime.

It is an emirp because it is prime and its reverse (199999931) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 139999991 - 2¹⁰ = 139998967 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 139999991.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (139999901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69999995 + 69999996.

It is an arithmetic number, because the mean of its divisors is an integer number (69999996).

Almost surely, 2^139999991 is an apocalyptic number.

139999991 is a deficient number, since it is larger than the sum of its proper divisors (1).

139999991 is an equidigital number, since it uses as much as digits as its factorization.

139999991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1594323, while the sum is 59.

The square root of 139999991 is about 11832.1591858798. The cubic root of 139999991 is about 519.2493990583.

The spelling of 139999991 in words is "one hundred thirty-nine million, nine hundred ninety-nine thousand, nine hundred ninety-one".