21122222021 has 4 divisors (see below), whose sum is σ = 21389592000. Its totient is φ = 20854852044.

The previous prime is 21122221973. The next prime is 21122222057. The reversal of 21122222021 is 12022222112.

It is a happy number.

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 21122222021 - 2³⁴ = 3942352837 is a prime.

It is a super-2 number, since 2×21122222021² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21122222071) 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, 133684871 + ... + 133685028.

It is an arithmetic number, because the mean of its divisors is an integer number (5347398000).

Almost surely, 2^21122222021 is an apocalyptic number.

It is an amenable number.

21122222021 is a deficient number, since it is larger than the sum of its proper divisors (267369979).

21122222021 is an equidigital number, since it uses as much as digits as its factorization.

21122222021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 267369978.

The product of its (nonzero) digits is 128, while the sum is 17.

Adding to 21122222021 its reverse (12022222112), we get a palindrome (33144444133).

Subtracting from 21122222021 its reverse (12022222112), we obtain a palindrome (9099999909).

The spelling of 21122222021 in words is "twenty-one billion, one hundred twenty-two million, two hundred twenty-two thousand, twenty-one".