138481691 has 2 divisors, whose sum is σ = 138481692. Its totient is φ = 138481690.

The previous prime is 138481687. The next prime is 138481727. The reversal of 138481691 is 196184831.

It is a weak prime.

It is an emirp because it is prime and its reverse (196184831) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 138481691 - 2² = 138481687 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (138481631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69240845 + 69240846.

It is an arithmetic number, because the mean of its divisors is an integer number (69240846).

Almost surely, 2^138481691 is an apocalyptic number.

138481691 is a deficient number, since it is larger than the sum of its proper divisors (1).

138481691 is an equidigital number, since it uses as much as digits as its factorization.

138481691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 41472, while the sum is 41.

The square root of 138481691 is about 11767.8243953587. The cubic root of 138481691 is about 517.3654855096.

The spelling of 138481691 in words is "one hundred thirty-eight million, four hundred eighty-one thousand, six hundred ninety-one".