161688889 has 4 divisors (see below), whose sum is σ = 164102224. Its totient is φ = 159275556.

The previous prime is 161688869. The next prime is 161688911. The reversal of 161688889 is 988886161.

161688889 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 161688889 - 2¹³ = 161680697 is a prime.

It is a super-2 number, since 2×161688889² = 52286593652108642, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161688859) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1206567 + ... + 1206700.

It is an arithmetic number, because the mean of its divisors is an integer number (41025556).

Almost surely, 2^161688889 is an apocalyptic number.

It is an amenable number.

161688889 is a deficient number, since it is larger than the sum of its proper divisors (2413335).

161688889 is an equidigital number, since it uses as much as digits as its factorization.

161688889 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2413334.

The product of its digits is 1327104, while the sum is 55.

The square root of 161688889 is about 12715.6945936901. The cubic root of 161688889 is about 544.7869874282.

The spelling of 161688889 in words is "one hundred sixty-one million, six hundred eighty-eight thousand, eight hundred eighty-nine".