21420203443321 has 4 divisors (see below), whose sum is σ = 21432096950644. Its totient is φ = 21408309936000.

The previous prime is 21420203443283. The next prime is 21420203443357. The reversal of 21420203443321 is 12334430202412.

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 3246522879721 + 18173680563600 = 1801811^2 + 4263060^2 .

It is a cyclic number.

It is not a de Polignac number, because 21420203443321 - 2⁷ = 21420203443193 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21420203443421) 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, 5946750960 + ... + 5946754561.

It is an arithmetic number, because the mean of its divisors is an integer number (5358024237661).

Almost surely, 2^{21420203443321} is an apocalyptic number.

It is an amenable number.

21420203443321 is a deficient number, since it is larger than the sum of its proper divisors (11893507323).

21420203443321 is a wasteful number, since it uses less digits than its factorization.

21420203443321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11893507322.

The product of its (nonzero) digits is 27648, while the sum is 31.

Adding to 21420203443321 its reverse (12334430202412), we get a palindrome (33754633645733).

The spelling of 21420203443321 in words is "twenty-one trillion, four hundred twenty billion, two hundred three million, four hundred forty-three thousand, three hundred twenty-one".