21201112021 has 4 divisors (see below), whose sum is σ = 21229119532. Its totient is φ = 21173104512.

The previous prime is 21201112003. The next prime is 21201112027. The reversal of 21201112021 is 12021110212.

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 14911828996 + 6289283025 = 122114^2 + 79305^2 .

It is a cyclic number.

It is not a de Polignac number, because 21201112021 - 2⁵ = 21201111989 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21201111992 and 21201112010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201112027) 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, 14002620 + ... + 14004133.

It is an arithmetic number, because the mean of its divisors is an integer number (5307279883).

Almost surely, 2^21201112021 is an apocalyptic number.

It is an amenable number.

21201112021 is a deficient number, since it is larger than the sum of its proper divisors (28007511).

21201112021 is an equidigital number, since it uses as much as digits as its factorization.

21201112021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28007510.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21201112021 its reverse (12021110212), we get a palindrome (33222222233).

The spelling of 21201112021 in words is "twenty-one billion, two hundred one million, one hundred twelve thousand, twenty-one".