21200000021 has 8 divisors (see below), whose sum is σ = 21535204320. Its totient is φ = 20866695472.

The previous prime is 21200000009. The next prime is 21200000023. The reversal of 21200000021 is 12000000212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21200000021 - 2¹⁸ = 21199737877 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21199999954 and 21200000008.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21200000023) 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 7 ways as a sum of consecutive naturals, for example, 452435 + ... + 497088.

It is an arithmetic number, because the mean of its divisors is an integer number (2691900540).

Almost surely, 2^21200000021 is an apocalyptic number.

It is an amenable number.

21200000021 is a deficient number, since it is larger than the sum of its proper divisors (335204299).

21200000021 is an equidigital number, since it uses as much as digits as its factorization.

21200000021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 949875.

The product of its (nonzero) digits is 8, while the sum is 8.

Adding to 21200000021 its reverse (12000000212), we get a palindrome (33200000233).

It can be divided in two parts, 2 and 1200000021, that multiplied together give a palindrome (2400000042).

The spelling of 21200000021 in words is "twenty-one billion, two hundred million, twenty-one", and thus it is an aban number.