161381 has 8 divisors (see below), whose sum is σ = 186624. Its totient is φ = 137920.

The previous prime is 161377. The next prime is 161387. The reversal of 161381 is 183161.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 161381 - 2² = 161377 is a prime.

It is a super-2 number, since 2×161381² = 52087654322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161387) 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, 245 + ... + 618.

It is an arithmetic number, because the mean of its divisors is an integer number (23328).

2¹⁶¹³⁸¹ is an apocalyptic number.

161381 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

161381 is a deficient number, since it is larger than the sum of its proper divisors (25243).

161381 is a wasteful number, since it uses less digits than its factorization.

161381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 891.

The product of its digits is 144, while the sum is 20.

The square root of 161381 is about 401.7225410653. The cubic root of 161381 is about 54.4440972104. Note that the first 3 decimals are identical.

The spelling of 161381 in words is "one hundred sixty-one thousand, three hundred eighty-one".