21122221112221 has 4 divisors (see below), whose sum is σ = 21122296251552. Its totient is φ = 21122145972892.

The previous prime is 21122221112207. The next prime is 21122221112243. The reversal of 21122221112221 is 12221112222112.

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-21122221112221 is a prime.

It is a super-2 number, since 2×21122221112221² (a number of 27 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 = 21122221112192 and 21122221112201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21122221112261) 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, 37146415 + ... + 37710748.

It is an arithmetic number, because the mean of its divisors is an integer number (5280574062888).

Almost surely, 2^{21122221112221} is an apocalyptic number.

It is an amenable number.

21122221112221 is a deficient number, since it is larger than the sum of its proper divisors (75139331).

21122221112221 is an equidigital number, since it uses as much as digits as its factorization.

21122221112221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75139330.

The product of its digits is 256, while the sum is 22.

Adding to 21122221112221 its reverse (12221112222112), we get a palindrome (33343333334333).

The spelling of 21122221112221 in words is "twenty-one trillion, one hundred twenty-two billion, two hundred twenty-one million, one hundred twelve thousand, two hundred twenty-one".