2145312221 has 4 divisors (see below), whose sum is σ = 2310336252. Its totient is φ = 1980288192.

The previous prime is 2145312193. The next prime is 2145312223. The reversal of 2145312221 is 1222135412.

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 1405200196 + 740112025 = 37486^2 + 27205^2 .

It is a cyclic number.

It is not a de Polignac number, because 2145312221 - 2¹⁸ = 2145050077 is a prime.

It is a super-4 number, since 4×2145312221⁴ (a number of 38 digits) contains 4444 as substring. Note that it is a super-d number also for d = 3.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2145312223) 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, 82511996 + ... + 82512021.

It is an arithmetic number, because the mean of its divisors is an integer number (577584063).

Almost surely, 2^2145312221 is an apocalyptic number.

It is an amenable number.

2145312221 is a deficient number, since it is larger than the sum of its proper divisors (165024031).

2145312221 is a wasteful number, since it uses less digits than its factorization.

2145312221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 165024030.

The product of its digits is 960, while the sum is 23.

The square root of 2145312221 is about 46317.5152723028. The cubic root of 2145312221 is about 1289.7241605197.

Adding to 2145312221 its reverse (1222135412), we get a palindrome (3367447633).

The spelling of 2145312221 in words is "two billion, one hundred forty-five million, three hundred twelve thousand, two hundred twenty-one".