169139561 has 2 divisors, whose sum is σ = 169139562. Its totient is φ = 169139560.

The previous prime is 169139497. The next prime is 169139563. The reversal of 169139561 is 165931961.

169139561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 106729561 + 62410000 = 10331^2 + 7900^2 .

It is a cyclic number.

It is not a de Polignac number, because 169139561 - 2⁶ = 169139497 is a prime.

Together with 169139563, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (169139563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 84569780 + 84569781.

It is an arithmetic number, because the mean of its divisors is an integer number (84569781).

Almost surely, 2^169139561 is an apocalyptic number.

It is an amenable number.

169139561 is a deficient number, since it is larger than the sum of its proper divisors (1).

169139561 is an equidigital number, since it uses as much as digits as its factorization.

169139561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 43740, while the sum is 41.

The square root of 169139561 is about 13005.3666230522. The cubic root of 169139561 is about 553.0296291079.

The spelling of 169139561 in words is "one hundred sixty-nine million, one hundred thirty-nine thousand, five hundred sixty-one".