209813643421 has 4 divisors (see below), whose sum is σ = 209818203100. Its totient is φ = 209809083744.

The previous prime is 209813643401. The next prime is 209813643433. The reversal of 209813643421 is 124346318902.

209813643421 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 50137479396 + 159676164025 = 223914^2 + 399595^2 .

It is a cyclic number.

It is not a de Polignac number, because 209813643421 - 2²⁵ = 209780088989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209813643401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2210106 + ... + 2303083.

It is an arithmetic number, because the mean of its divisors is an integer number (52454550775).

Almost surely, 2^209813643421 is an apocalyptic number.

It is an amenable number.

209813643421 is a deficient number, since it is larger than the sum of its proper divisors (4559679).

209813643421 is an equidigital number, since it uses as much as digits as its factorization.

209813643421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4559678.

The product of its (nonzero) digits is 248832, while the sum is 43.

The spelling of 209813643421 in words is "two hundred nine billion, eight hundred thirteen million, six hundred forty-three thousand, four hundred twenty-one".