221421204073645 has 4 divisors (see below), whose sum is σ = 265705444888380. Its totient is φ = 177136963258912.

The previous prime is 221421204073633. The next prime is 221421204073669. The reversal of 221421204073645 is 546370402124122.

221421204073645 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 63693376140969 + 157727827932676 = 7980813^2 + 12558974^2 .

It is a cyclic number.

It is not a de Polignac number, because 221421204073645 - 2¹¹ = 221421204071597 is a prime.

It is a super-3 number, since 3×221421204073645³ (a number of 44 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22142120407360 + ... + 22142120407369.

It is an arithmetic number, because the mean of its divisors is an integer number (66426361222095).

Almost surely, 2^{221421204073645} is an apocalyptic number.

It is an amenable number.

221421204073645 is a deficient number, since it is larger than the sum of its proper divisors (44284240814735).

221421204073645 is an equidigital number, since it uses as much as digits as its factorization.

221421204073645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44284240814734.

The product of its (nonzero) digits is 645120, while the sum is 43.

Adding to 221421204073645 its reverse (546370402124122), we get a palindrome (767791606197767).

The spelling of 221421204073645 in words is "two hundred twenty-one trillion, four hundred twenty-one billion, two hundred four million, seventy-three thousand, six hundred forty-five".