165561408 has 140 divisors (see below), whose sum is σ = 496968780. Its totient is φ = 54494208.

The previous prime is 165561397. The next prime is 165561467. The reversal of 165561408 is 804165561.

It can be written as a sum of positive squares in 2 ways, for example, as 139428864 + 26132544 = 11808^2 + 5112^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

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 19 ways as a sum of consecutive naturals, for example, 564910 + ... + 565202.

It is an arithmetic number, because the mean of its divisors is an integer number (3549777).

Almost surely, 2^165561408 is an apocalyptic number.

165561408 is a gapful number since it is divisible by the number (18) 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 165561408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (248484390).

165561408 is an abundant number, since it is smaller than the sum of its proper divisors (331407372).

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

165561408 is a wasteful number, since it uses less digits than its factorization.

165561408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 426 (or 407 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 36.

The square root of 165561408 is about 12867.0667986142. The cubic root of 165561408 is about 549.1020145461.

It can be divided in two parts, 1 and 65561408, that added together give a square (65561409 = 8097²).

The spelling of 165561408 in words is "one hundred sixty-five million, five hundred sixty-one thousand, four hundred eight".