21320002000021 has 4 divisors (see below), whose sum is σ = 21840002048844. Its totient is φ = 20800001951200.

The previous prime is 21320001999973. The next prime is 21320002000051. The reversal of 21320002000021 is 12000020002312.

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 4800857859396 + 16519144140625 = 2191086^2 + 4064375^2 .

It is a cyclic number.

It is not a de Polignac number, because 21320002000021 - 2¹⁹ = 21320001475733 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21320001999965 and 21320002000010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21320002000051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 260000024350 + ... + 260000024431.

It is an arithmetic number, because the mean of its divisors is an integer number (5460000512211).

Almost surely, 2^{21320002000021} is an apocalyptic number.

It is an amenable number.

21320002000021 is a deficient number, since it is larger than the sum of its proper divisors (520000048823).

21320002000021 is an equidigital number, since it uses as much as digits as its factorization.

21320002000021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 520000048822.

The product of its (nonzero) digits is 48, while the sum is 13.

Adding to 21320002000021 its reverse (12000020002312), we get a palindrome (33320022002333).

The spelling of 21320002000021 in words is "twenty-one trillion, three hundred twenty billion, two million, twenty-one", and thus it is an aban number.