161982381 has 16 divisors (see below), whose sum is σ = 237178368. Its totient is φ = 97518000.

The previous prime is 161982377. The next prime is 161982397. The reversal of 161982381 is 183289161.

It is not a de Polignac number, because 161982381 - 2² = 161982377 is a prime.

It is a super-2 number, since 2×161982381² = 52476583508858322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161982181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11271 + ... + 21236.

It is an arithmetic number, because the mean of its divisors is an integer number (14823648).

Almost surely, 2^161982381 is an apocalyptic number.

161982381 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

161982381 is a deficient number, since it is larger than the sum of its proper divisors (75195987).

161982381 is a wasteful number, since it uses less digits than its factorization.

161982381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32672.

The product of its digits is 20736, while the sum is 39.

The square root of 161982381 is about 12727.2299028500. The cubic root of 161982381 is about 545.1164142642.

The spelling of 161982381 in words is "one hundred sixty-one million, nine hundred eighty-two thousand, three hundred eighty-one".