21310210021 has 4 divisors (see below), whose sum is σ = 21347143372. Its totient is φ = 21273276672.

The previous prime is 21310210007. The next prime is 21310210049. The reversal of 21310210021 is 12001201312.

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 19934616100 + 1375593921 = 141190^2 + 37089^2 .

It is a cyclic number.

It is not a de Polignac number, because 21310210021 - 2⁹ = 21310209509 is a prime.

It is a super-2 number, since 2×21310210021² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21310209983 and 21310210010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21310210081) 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, 18465810 + ... + 18466963.

It is an arithmetic number, because the mean of its divisors is an integer number (5336785843).

Almost surely, 2^21310210021 is an apocalyptic number.

It is an amenable number.

21310210021 is a deficient number, since it is larger than the sum of its proper divisors (36933351).

21310210021 is an equidigital number, since it uses as much as digits as its factorization.

21310210021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36933350.

The product of its (nonzero) digits is 24, while the sum is 13.

Adding to 21310210021 its reverse (12001201312), we get a palindrome (33311411333).

The spelling of 21310210021 in words is "twenty-one billion, three hundred ten million, two hundred ten thousand, twenty-one".