2165121200 has 120 divisors (see below), whose sum is σ = 5699206656. Its totient is φ = 783904000.

The previous prime is 2165121199. The next prime is 2165121229. The reversal of 2165121200 is 21215612.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1156265 + ... + 1158135.

Almost surely, 2^2165121200 is an apocalyptic number.

2165121200 is a gapful number since it is divisible by the number (20) 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 2165121200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2849603328).

2165121200 is an abundant number, since it is smaller than the sum of its proper divisors (3534085456).

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

2165121200 is a wasteful number, since it uses less digits than its factorization.

2165121200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2163 (or 2152 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 20.

The square root of 2165121200 is about 46530.8628761599. The cubic root of 2165121200 is about 1293.6816087133.

Adding to 2165121200 its reverse (21215612), we get a palindrome (2186336812).

It can be divided in two parts, 216512 and 1200, that added together give a palindrome (217712).

The spelling of 2165121200 in words is "two billion, one hundred sixty-five million, one hundred twenty-one thousand, two hundred".