161978290 has 16 divisors (see below), whose sum is σ = 298672920. Its totient is φ = 63210880.

The previous prime is 161978273. The next prime is 161978293. The reversal of 161978290 is 92879161.

161978290 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 63154809 + 98823481 = 7947^2 + 9941^2 .

It is not an unprimeable number, because it can be changed into a prime (161978293) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 197125 + ... + 197944.

Almost surely, 2^161978290 is an apocalyptic number.

161978290 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

161978290 is a deficient number, since it is larger than the sum of its proper divisors (136694630).

161978290 is a wasteful number, since it uses less digits than its factorization.

161978290 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 395117.

The product of its (nonzero) digits is 54432, while the sum is 43.

The square root of 161978290 is about 12727.0691834373. The cubic root of 161978290 is about 545.1118251025. Note that the first 3 decimals are identical.

The spelling of 161978290 in words is "one hundred sixty-one million, nine hundred seventy-eight thousand, two hundred ninety".