161991768 has 16 divisors (see below), whose sum is σ = 404979480. Its totient is φ = 53997248.

The previous prime is 161991761. The next prime is 161991799. The reversal of 161991768 is 867199161.

161991768 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-3 number, since 3×161991768³ (a number of 26 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161991761) 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, 3374805 + ... + 3374852.

Almost surely, 2^161991768 is an apocalyptic number.

It is an amenable number.

161991768 is an abundant number, since it is smaller than the sum of its proper divisors (242987712).

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

161991768 is a wasteful number, since it uses less digits than its factorization.

161991768 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6749666 (or 6749662 counting only the distinct ones).

The product of its digits is 163296, while the sum is 48.

The square root of 161991768 is about 12727.5986737483. The cubic root of 161991768 is about 545.1269440286.

The spelling of 161991768 in words is "one hundred sixty-one million, nine hundred ninety-one thousand, seven hundred sixty-eight".