165997840 has 40 divisors (see below), whose sum is σ = 387921600. Its totient is φ = 66059136.

The previous prime is 165997781. The next prime is 165997841. The reversal of 165997840 is 48799561.

It is a tau number, because it is divible by the number of its divisors (40).

It is not an unprimeable number, because it can be changed into a prime (165997841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10707 + ... + 21133.

It is an arithmetic number, because the mean of its divisors is an integer number (9698040).

Almost surely, 2^165997840 is an apocalyptic number.

165997840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

165997840 is an abundant number, since it is smaller than the sum of its proper divisors (221923760).

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

165997840 is a wasteful number, since it uses less digits than its factorization.

165997840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10639 (or 10633 counting only the distinct ones).

The product of its (nonzero) digits is 544320, while the sum is 49.

The square root of 165997840 is about 12884.0149021957. The cubic root of 165997840 is about 549.5840822506.

It can be divided in two parts, 1659 and 97840, that added together give a palindrome (99499).

The spelling of 165997840 in words is "one hundred sixty-five million, nine hundred ninety-seven thousand, eight hundred forty".