165989988 has 72 divisors (see below), whose sum is σ = 439927488. Its totient is φ = 52671168.

The previous prime is 165989987. The next prime is 165990037. The reversal of 165989988 is 889989561.

165989988 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×165989988² = 55105352232480288, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (165989987) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 253870 + ... + 254522.

It is an arithmetic number, because the mean of its divisors is an integer number (6110104).

Almost surely, 2^165989988 is an apocalyptic number.

165989988 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 165989988, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (219963744).

165989988 is an abundant number, since it is smaller than the sum of its proper divisors (273937500).

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

165989988 is a wasteful number, since it uses less digits than its factorization.

165989988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 993 (or 988 counting only the distinct ones).

The product of its digits is 11197440, while the sum is 63.

The square root of 165989988 is about 12883.7101799132. The cubic root of 165989988 is about 549.5754166715.

The spelling of 165989988 in words is "one hundred sixty-five million, nine hundred eighty-nine thousand, nine hundred eighty-eight".