21122120221 has 4 divisors (see below), whose sum is σ = 21419614944. Its totient is φ = 20824625500.

The previous prime is 21122120209. The next prime is 21122120231. The reversal of 21122120221 is 12202122112.

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 21122120221 - 2¹³ = 21122112029 is a prime.

It is a super-2 number, since 2×21122120221² (a number of 21 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 = 21122120195 and 21122120204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21122120231) 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, 148747255 + ... + 148747396.

It is an arithmetic number, because the mean of its divisors is an integer number (5354903736).

Almost surely, 2^21122120221 is an apocalyptic number.

It is an amenable number.

21122120221 is a deficient number, since it is larger than the sum of its proper divisors (297494723).

21122120221 is an equidigital number, since it uses as much as digits as its factorization.

21122120221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 297494722.

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

Adding to 21122120221 its reverse (12202122112), we get a palindrome (33324242333).

The spelling of 21122120221 in words is "twenty-one billion, one hundred twenty-two million, one hundred twenty thousand, two hundred twenty-one".