2165222400221 has 4 divisors (see below), whose sum is σ = 2165280428892. Its totient is φ = 2165164371552.

The previous prime is 2165222400217. The next prime is 2165222400283. The reversal of 2165222400221 is 1220042225612.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1421195395321 + 744027004900 = 1192139^2 + 862570^2 .

It is a cyclic number.

It is not a de Polignac number, because 2165222400221 - 2² = 2165222400217 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2165222430221) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 28958330 + ... + 29033003.

It is an arithmetic number, because the mean of its divisors is an integer number (541320107223).

Almost surely, 2^{2165222400221} is an apocalyptic number.

It is an amenable number.

2165222400221 is a deficient number, since it is larger than the sum of its proper divisors (58028671).

2165222400221 is an equidigital number, since it uses as much as digits as its factorization.

2165222400221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58028670.

The product of its (nonzero) digits is 7680, while the sum is 29.

Adding to 2165222400221 its reverse (1220042225612), we get a palindrome (3385264625833).

The spelling of 2165222400221 in words is "two trillion, one hundred sixty-five billion, two hundred twenty-two million, four hundred thousand, two hundred twenty-one".