20401220321 has 4 divisors (see below), whose sum is σ = 20952604692. Its totient is φ = 19849835952.

The previous prime is 20401220309. The next prime is 20401220327. The reversal of 20401220321 is 12302210402.

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 17839342096 + 2561878225 = 133564^2 + 50615^2 .

It is a cyclic number.

It is not a de Polignac number, because 20401220321 - 2¹⁴ = 20401203937 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20401220321.

It is not an unprimeable number, because it can be changed into a prime (20401220327) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 275692130 + ... + 275692203.

It is an arithmetic number, because the mean of its divisors is an integer number (5238151173).

Almost surely, 2^20401220321 is an apocalyptic number.

It is an amenable number.

20401220321 is a deficient number, since it is larger than the sum of its proper divisors (551384371).

20401220321 is an equidigital number, since it uses as much as digits as its factorization.

20401220321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 551384370.

The product of its (nonzero) digits is 192, while the sum is 17.

Adding to 20401220321 its reverse (12302210402), we get a palindrome (32703430723).

The spelling of 20401220321 in words is "twenty billion, four hundred one million, two hundred twenty thousand, three hundred twenty-one".