161861 has 8 divisors (see below), whose sum is σ = 194880. Its totient is φ = 131328.

The previous prime is 161839. The next prime is 161869. The reversal of 161861 is 168161.

It is a happy number.

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

It is not a de Polignac number, because 161861 - 2¹⁴ = 145477 is a prime.

It is a plaindrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161869) 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, 476 + ... + 741.

It is an arithmetic number, because the mean of its divisors is an integer number (24360).

2¹⁶¹⁸⁶¹ is an apocalyptic number.

It is an amenable number.

161861 is a deficient number, since it is larger than the sum of its proper divisors (33019).

161861 is a wasteful number, since it uses less digits than its factorization.

161861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1243.

The product of its digits is 288, while the sum is 23.

The square root of 161861 is about 402.3195247561. The cubic root of 161861 is about 54.4980219802.

The spelling of 161861 in words is "one hundred sixty-one thousand, eight hundred sixty-one".