21211222021 has 16 divisors (see below), whose sum is σ = 23990904000. Its totient is φ = 18576409600.

The previous prime is 21211221991. The next prime is 21211222051. The reversal of 21211222021 is 12022211212.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21211221991) and next prime (21211222051).

It is a cyclic number.

It is not a de Polignac number, because 21211222021 - 2⁷ = 21211221893 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21211221986 and 21211222004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211222051) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 69186 + ... + 217276.

It is an arithmetic number, because the mean of its divisors is an integer number (1499431500).

Almost surely, 2^21211222021 is an apocalyptic number.

It is an amenable number.

21211222021 is a deficient number, since it is larger than the sum of its proper divisors (2779681979).

21211222021 is a wasteful number, since it uses less digits than its factorization.

21211222021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 148580.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21211222021 its reverse (12022211212), we get a palindrome (33233433233).

The spelling of 21211222021 in words is "twenty-one billion, two hundred eleven million, two hundred twenty-two thousand, twenty-one".