165641640 has 128 divisors (see below), whose sum is σ = 514926720. Its totient is φ = 42598400.

The previous prime is 165641617. The next prime is 165641647. The reversal of 165641640 is 46146561.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (165641647) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 644392 + ... + 644648.

It is an arithmetic number, because the mean of its divisors is an integer number (4022865).

Almost surely, 2^165641640 is an apocalyptic number.

165641640 is a gapful number since it is divisible by the number (10) 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 165641640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (257463360).

165641640 is an abundant number, since it is smaller than the sum of its proper divisors (349285080).

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

165641640 is a wasteful number, since it uses less digits than its factorization.

165641640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 443 (or 439 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 33.

The square root of 165641640 is about 12870.1841478667. The cubic root of 165641640 is about 549.1906995417.

The spelling of 165641640 in words is "one hundred sixty-five million, six hundred forty-one thousand, six hundred forty".