21211000021 has 4 divisors (see below), whose sum is σ = 21245267200. Its totient is φ = 21176732844.

The previous prime is 21210999989. The next prime is 21211000073. The reversal of 21211000021 is 12000011212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21211000021 - 2⁵ = 21210999989 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21210999971 and 21211000007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211004021) 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, 17132661 + ... + 17133898.

It is an arithmetic number, because the mean of its divisors is an integer number (5311316800).

Almost surely, 2^21211000021 is an apocalyptic number.

It is an amenable number.

21211000021 is a deficient number, since it is larger than the sum of its proper divisors (34267179).

21211000021 is an equidigital number, since it uses as much as digits as its factorization.

21211000021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34267178.

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 21211000021 its reverse (12000011212), we get a palindrome (33211011233).

The spelling of 21211000021 in words is "twenty-one billion, two hundred eleven million, twenty-one", and thus it is an aban number.