21011222021 has 4 divisors (see below), whose sum is σ = 21012680544. Its totient is φ = 21009763500.

The previous prime is 21011221997. The next prime is 21011222047. The reversal of 21011222021 is 12022211012.

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 a de Polignac number, because none of the positive numbers 2^k-21011222021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21011221987 and 21011222005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011222051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 707435 + ... + 736536.

It is an arithmetic number, because the mean of its divisors is an integer number (5253170136).

Almost surely, 2^21011222021 is an apocalyptic number.

It is an amenable number.

21011222021 is a deficient number, since it is larger than the sum of its proper divisors (1458523).

21011222021 is a wasteful number, since it uses less digits than its factorization.

21011222021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1458522.

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21011222021 its reverse (12022211012), we get a palindrome (33033433033).

The spelling of 21011222021 in words is "twenty-one billion, eleven million, two hundred twenty-two thousand, twenty-one".