165688640 has 56 divisors (see below), whose sum is σ = 424906440. Its totient is φ = 61175808.

The previous prime is 165688639. The next prime is 165688643. The reversal of 165688640 is 46886561.

It can be written as a sum of positive squares in 4 ways, for example, as 24364096 + 141324544 = 4936^2 + 11888^2 .

It is a junction number, because it is equal to n+sod(n) for n = 165688591 and 165688600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165688643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15755 + ... + 24074.

It is an arithmetic number, because the mean of its divisors is an integer number (7587615).

Almost surely, 2^165688640 is an apocalyptic number.

165688640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

165688640 is an abundant number, since it is smaller than the sum of its proper divisors (259217800).

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

165688640 is a wasteful number, since it uses less digits than its factorization.

165688640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39859 (or 39849 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 44.

The square root of 165688640 is about 12872.0099440608. The cubic root of 165688640 is about 549.2426380155.

The spelling of 165688640 in words is "one hundred sixty-five million, six hundred eighty-eight thousand, six hundred forty".