161990 has 16 divisors (see below), whose sum is σ = 296352. Its totient is φ = 63744.

The previous prime is 161983. The next prime is 161999. The reversal of 161990 is 99161.

161990 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161999) by changing a digit.

161990 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 887 + ... + 1053.

It is an arithmetic number, because the mean of its divisors is an integer number (18522).

2¹⁶¹⁹⁹⁰ is an apocalyptic number.

161990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

161990 is a deficient number, since it is larger than the sum of its proper divisors (134362).

161990 is a wasteful number, since it uses less digits than its factorization.

161990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 271.

The product of its (nonzero) digits is 486, while the sum is 26.

The square root of 161990 is about 402.4798131584. The cubic root of 161990 is about 54.5124960825.

The spelling of 161990 in words is "one hundred sixty-one thousand, nine hundred ninety".