161931 has 16 divisors (see below), whose sum is σ = 269568. Its totient is φ = 84000.

The previous prime is 161923. The next prime is 161947. The reversal of 161931 is 139161.

It is a happy number.

161931 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 161931 - 2³ = 161923 is a prime.

It is a super-2 number, since 2×161931² = 52443297522, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a plaindrome in base 16.

It is a junction number, because it is equal to n+sod(n) for n = 161898 and 161907.

It is not an unprimeable number, because it can be changed into a prime (161911) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 120 + ... + 581.

It is an arithmetic number, because the mean of its divisors is an integer number (16848).

2¹⁶¹⁹³¹ is an apocalyptic number.

161931 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

161931 is a deficient number, since it is larger than the sum of its proper divisors (107637).

161931 is a wasteful number, since it uses less digits than its factorization.

161931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 722.

The product of its digits is 162, while the sum is 21.

The square root of 161931 is about 402.4065108817. The cubic root of 161931 is about 54.5058770982.

The spelling of 161931 in words is "one hundred sixty-one thousand, nine hundred thirty-one".