161648640 has 156 divisors (see below), whose sum is σ = 560952444. Its totient is φ = 43057152.

The previous prime is 161648593. The next prime is 161648677. The reversal of 161648640 is 46846161.

161648640 is a `hidden beast` number, since 1 + 6 + 1 + 6 + 4 + 8 + 640 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 99680256 + 61968384 = 9984^2 + 7872^2 .

It is a super-2 number, since 2×161648640² = 52260565627699200, which contains 22 as substring.

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

It is a junction number, because it is equal to n+sod(n) for n = 161648595 and 161648604.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 183882 + ... + 184758.

It is an arithmetic number, because the mean of its divisors is an integer number (3595849).

Almost surely, 2^161648640 is an apocalyptic number.

161648640 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 161648640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (280476222).

161648640 is an abundant number, since it is smaller than the sum of its proper divisors (399303804).

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

161648640 is an equidigital number, since it uses as much as digits as its factorization.

161648640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 912 (or 887 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 36.

The square root of 161648640 is about 12714.1118447181. Note that the first 3 decimals coincide. The cubic root of 161648640 is about 544.7417793102.

It can be divided in two parts, 16 and 1648640, that added together give a square (1648656 = 1284²).

The spelling of 161648640 in words is "one hundred sixty-one million, six hundred forty-eight thousand, six hundred forty".