161978823 has 12 divisors (see below), whose sum is σ = 239676528. Its totient is φ = 105351840.

The previous prime is 161978821. The next prime is 161978863. The reversal of 161978823 is 328879161.

161978823 is a `hidden beast` number, since 1 + 619 + 7 + 8 + 8 + 23 = 666.

It is not a de Polignac number, because 161978823 - 2¹ = 161978821 is a prime.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161978821) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 219115 + ... + 219852.

It is an arithmetic number, because the mean of its divisors is an integer number (19973044).

Almost surely, 2^161978823 is an apocalyptic number.

161978823 is a deficient number, since it is larger than the sum of its proper divisors (77697705).

161978823 is a wasteful number, since it uses less digits than its factorization.

161978823 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 439014 (or 439011 counting only the distinct ones).

The product of its digits is 145152, while the sum is 45.

The square root of 161978823 is about 12727.0901230407. The cubic root of 161978823 is about 545.1124230103.

The spelling of 161978823 in words is "one hundred sixty-one million, nine hundred seventy-eight thousand, eight hundred twenty-three".