161688436 has 144 divisors (see below), whose sum is σ = 386104320. Its totient is φ = 58544640.

The previous prime is 161688433. The next prime is 161688437. The reversal of 161688436 is 634886161.

It is a happy number.

161688436 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×161688436² = 52286300672252192, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 161688392 and 161688401.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161688433) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1816680 + ... + 1816768.

It is an arithmetic number, because the mean of its divisors is an integer number (2681280).

Almost surely, 2^161688436 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 161688436, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (193052160).

161688436 is an abundant number, since it is smaller than the sum of its proper divisors (224415884).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

161688436 is a wasteful number, since it uses less digits than its factorization.

161688436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 174 (or 165 counting only the distinct ones).

The product of its digits is 165888, while the sum is 43.

The square root of 161688436 is about 12715.6767810447. The cubic root of 161688436 is about 544.7864786554.

The spelling of 161688436 in words is "one hundred sixty-one million, six hundred eighty-eight thousand, four hundred thirty-six".