21221120000021 has 4 divisors (see below), whose sum is σ = 21224614344972. Its totient is φ = 21217625655072.

The previous prime is 21221119999999. The next prime is 21221120000083. The reversal of 21221120000021 is 12000002112212.

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 12453036400996 + 8768083599025 = 3528886^2 + 2961095^2 .

It is a cyclic number.

It is not a de Polignac number, because 21221120000021 - 2¹⁸ = 21221119737877 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21221119999960 and 21221120000005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221120005021) 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, 1747163366 + ... + 1747175511.

It is an arithmetic number, because the mean of its divisors is an integer number (5306153586243).

Almost surely, 2^{21221120000021} is an apocalyptic number.

It is an amenable number.

21221120000021 is a deficient number, since it is larger than the sum of its proper divisors (3494344951).

21221120000021 is an equidigital number, since it uses as much as digits as its factorization.

21221120000021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3494344950.

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21221120000021 its reverse (12000002112212), we get a palindrome (33221122112233).

The spelling of 21221120000021 in words is "twenty-one trillion, two hundred twenty-one billion, one hundred twenty million, twenty-one", and thus it is an aban number.