161988 has 12 divisors (see below), whose sum is σ = 378000. Its totient is φ = 53992.

The previous prime is 161983. The next prime is 161999. The reversal of 161988 is 889161.

It is a tau number, because it is divible by the number of its divisors (12).

It is a super-2 number, since 2×161988² = 52480224288, which contains 22 as substring.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (161983) by changing a digit.

161988 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 3 ways as a sum of consecutive naturals, for example, 6738 + ... + 6761.

It is an arithmetic number, because the mean of its divisors is an integer number (31500).

2¹⁶¹⁹⁸⁸ is an apocalyptic number.

It is an amenable number.

161988 is an abundant number, since it is smaller than the sum of its proper divisors (216012).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

161988 is a wasteful number, since it uses less digits than its factorization.

161988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13506 (or 13504 counting only the distinct ones).

The product of its digits is 3456, while the sum is 33.

The square root of 161988 is about 402.4773285540. The cubic root of 161988 is about 54.5122717365.

The spelling of 161988 in words is "one hundred sixty-one thousand, nine hundred eighty-eight".