165861840 has 80 divisors (see below), whose sum is σ = 521270208. Its totient is φ = 43619328.

The previous prime is 165861833. The next prime is 165861853. The reversal of 165861840 is 48168561.

165861840 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12787 + ... + 22253.

Almost surely, 2^165861840 is an apocalyptic number.

165861840 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 165861840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (260635104).

165861840 is an abundant number, since it is smaller than the sum of its proper divisors (355408368).

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

165861840 is a wasteful number, since it uses less digits than its factorization.

165861840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9556 (or 9550 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 39.

The square root of 165861840 is about 12878.7359628187. The cubic root of 165861840 is about 549.4339520710.

The spelling of 165861840 in words is "one hundred sixty-five million, eight hundred sixty-one thousand, eight hundred forty".