21221203021 has 8 divisors (see below), whose sum is σ = 21835683864. Its totient is φ = 20614651200.

The previous prime is 21221203019. The next prime is 21221203027. The reversal of 21221203021 is 12030212212.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 3707592100 + 17513610921 = 60890^2 + 132339^2 .

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 21221203021 - 2¹ = 21221203019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21221202986 and 21221203004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221203027) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1976826 + ... + 1987531.

It is an arithmetic number, because the mean of its divisors is an integer number (2729460483).

Almost surely, 2^21221203021 is an apocalyptic number.

It is an amenable number.

21221203021 is a deficient number, since it is larger than the sum of its proper divisors (614480843).

21221203021 is a wasteful number, since it uses less digits than its factorization.

21221203021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3964511.

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 21221203021 its reverse (12030212212), we get a palindrome (33251415233).

The spelling of 21221203021 in words is "twenty-one billion, two hundred twenty-one million, two hundred three thousand, twenty-one".