161881639 has 2 divisors, whose sum is σ = 161881640. Its totient is φ = 161881638.

The previous prime is 161881591. The next prime is 161881649. The reversal of 161881639 is 936188161.

It is a happy number.

161881639 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 is an emirp because it is prime and its reverse (936188161) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 161881639 - 2¹¹ = 161879591 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 161881595 and 161881604.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161881649) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80940819 + 80940820.

It is an arithmetic number, because the mean of its divisors is an integer number (80940820).

Almost surely, 2^161881639 is an apocalyptic number.

161881639 is a deficient number, since it is larger than the sum of its proper divisors (1).

161881639 is an equidigital number, since it uses as much as digits as its factorization.

161881639 is an evil number, because the sum of its binary digits is even.

The product of its digits is 62208, while the sum is 43.

The square root of 161881639 is about 12723.2715525528. The cubic root of 161881639 is about 545.0033824103.

The spelling of 161881639 in words is "one hundred sixty-one million, eight hundred eighty-one thousand, six hundred thirty-nine".