21323333021 has 4 divisors (see below), whose sum is σ = 21330239100. Its totient is φ = 21316426944.

The previous prime is 21323332991. The next prime is 21323333023. The reversal of 21323333021 is 12033332312.

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 19751210521 + 1572122500 = 140539^2 + 39650^2 .

It is a cyclic number.

It is not a de Polignac number, because 21323333021 - 2³⁴ = 4143463837 is a prime.

It is a super-2 number, since 2×21323333021² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21323333023) 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, 3448406 + ... + 3454583.

It is an arithmetic number, because the mean of its divisors is an integer number (5332559775).

Almost surely, 2^21323333021 is an apocalyptic number.

It is an amenable number.

21323333021 is a deficient number, since it is larger than the sum of its proper divisors (6906079).

21323333021 is an equidigital number, since it uses as much as digits as its factorization.

21323333021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6906078.

The product of its (nonzero) digits is 1944, while the sum is 23.

Adding to 21323333021 its reverse (12033332312), we get a palindrome (33356665333).

The spelling of 21323333021 in words is "twenty-one billion, three hundred twenty-three million, three hundred thirty-three thousand, twenty-one".