138561691 has 2 divisors, whose sum is σ = 138561692. Its totient is φ = 138561690.

The previous prime is 138561671. The next prime is 138561701. The reversal of 138561691 is 196165831.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 138561691 - 2⁵ = 138561659 is a prime.

It is a Chen prime.

It is equal to p_7835395 and since 138561691 and 7835395 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (138561601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69280845 + 69280846.

It is an arithmetic number, because the mean of its divisors is an integer number (69280846).

Almost surely, 2^138561691 is an apocalyptic number.

138561691 is a deficient number, since it is larger than the sum of its proper divisors (1).

138561691 is an equidigital number, since it uses as much as digits as its factorization.

138561691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 38880, while the sum is 40.

The square root of 138561691 is about 11771.2230035795. The cubic root of 138561691 is about 517.4650925912.

The spelling of 138561691 in words is "one hundred thirty-eight million, five hundred sixty-one thousand, six hundred ninety-one".