21201203021 has 4 divisors (see below), whose sum is σ = 21206336892. Its totient is φ = 21196069152.

The previous prime is 21201202993. The next prime is 21201203041. The reversal of 21201203021 is 12030210212.

It is a happy number.

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 8975478121 + 12225724900 = 94739^2 + 110570^2 .

It is a cyclic number.

It is not a de Polignac number, because 21201203021 - 2¹⁰ = 21201201997 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21201202987 and 21201203005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201203041) 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, 2560736 + ... + 2569001.

It is an arithmetic number, because the mean of its divisors is an integer number (5301584223).

Almost surely, 2^21201203021 is an apocalyptic number.

It is an amenable number.

21201203021 is a deficient number, since it is larger than the sum of its proper divisors (5133871).

21201203021 is an equidigital number, since it uses as much as digits as its factorization.

21201203021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5133870.

The product of its (nonzero) digits is 48, while the sum is 14.

Adding to 21201203021 its reverse (12030210212), we get a palindrome (33231413233).

The spelling of 21201203021 in words is "twenty-one billion, two hundred one million, two hundred three thousand, twenty-one".