166321220 has 24 divisors (see below), whose sum is σ = 376142424. Its totient is φ = 61410816.

The previous prime is 166321219. The next prime is 166321223. The reversal of 166321220 is 22123661.

166321220 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 34668544 + 131652676 = 5888^2 + 11474^2 .

It is not an unprimeable number, because it can be changed into a prime (166321223) 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, 319589 + ... + 320108.

It is an arithmetic number, because the mean of its divisors is an integer number (15672601).

Almost surely, 2^166321220 is an apocalyptic number.

166321220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

166321220 is an abundant number, since it is smaller than the sum of its proper divisors (209821204).

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

166321220 is a wasteful number, since it uses less digits than its factorization.

166321220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 639719 (or 639717 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 166321220 is about 12896.5584556501. The cubic root of 166321220 is about 549.9407319055.

Adding to 166321220 its reverse (22123661), we get a palindrome (188444881).

It can be divided in two parts, 16 and 6321220, that added together give a palindrome (6321236).

The spelling of 166321220 in words is "one hundred sixty-six million, three hundred twenty-one thousand, two hundred twenty".