21000221321 has 4 divisors (see below), whose sum is σ = 21001235712. Its totient is φ = 20999206932.

The previous prime is 21000221309. The next prime is 21000221339. The reversal of 21000221321 is 12312200012.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21000221321 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21000221296 and 21000221305.

It is not an unprimeable number, because it can be changed into a prime (21000221521) 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, 475481 + ... + 517766.

It is an arithmetic number, because the mean of its divisors is an integer number (5250308928).

Almost surely, 2^21000221321 is an apocalyptic number.

It is an amenable number.

21000221321 is a deficient number, since it is larger than the sum of its proper divisors (1014391).

21000221321 is an equidigital number, since it uses as much as digits as its factorization.

21000221321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1014390.

The product of its (nonzero) digits is 48, while the sum is 14.

Adding to 21000221321 its reverse (12312200012), we get a palindrome (33312421333).

The spelling of 21000221321 in words is "twenty-one billion, two hundred twenty-one thousand, three hundred twenty-one".