21310000021 has 4 divisors (see below), whose sum is σ = 22563529452. Its totient is φ = 20056470592.

The previous prime is 21310000013. The next prime is 21310000091. The reversal of 21310000021 is 12000001312.

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 6251274225 + 15058725796 = 79065^2 + 122714^2 .

It is a cyclic number.

It is not a de Polignac number, because 21310000021 - 2³ = 21310000013 is a prime.

It is a super-2 number, since 2×21310000021² (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 = 21309999962 and 21310000007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21310000091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 626764690 + ... + 626764723.

It is an arithmetic number, because the mean of its divisors is an integer number (5640882363).

Almost surely, 2^21310000021 is an apocalyptic number.

It is an amenable number.

21310000021 is a deficient number, since it is larger than the sum of its proper divisors (1253529431).

21310000021 is a wasteful number, since it uses less digits than its factorization.

21310000021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1253529430.

The product of its (nonzero) digits is 12, while the sum is 10.

Adding to 21310000021 its reverse (12000001312), we get a palindrome (33310001333).

The spelling of 21310000021 in words is "twenty-one billion, three hundred ten million, twenty-one", and thus it is an aban number.