165819906 has 64 divisors (see below), whose sum is σ = 425318400. Its totient is φ = 46906128.

The previous prime is 165819893. The next prime is 165819919. The reversal of 165819906 is 609918561.

It is an interprime number because it is at equal distance from previous prime (165819893) and next prime (165819919).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 36805 + ... + 41063.

It is an arithmetic number, because the mean of its divisors is an integer number (6645600).

Almost surely, 2^165819906 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 165819906, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (212659200).

165819906 is an abundant number, since it is smaller than the sum of its proper divisors (259498494).

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

165819906 is a wasteful number, since it uses less digits than its factorization.

165819906 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4380 (or 4374 counting only the distinct ones).

The product of its (nonzero) digits is 116640, while the sum is 45.

The square root of 165819906 is about 12877.1078274588. The cubic root of 165819906 is about 549.3876446437.

The spelling of 165819906 in words is "one hundred sixty-five million, eight hundred nineteen thousand, nine hundred six".