21210120221 has 4 divisors (see below), whose sum is σ = 21294622944. Its totient is φ = 21125617500.

The previous prime is 21210120209. The next prime is 21210120257. The reversal of 21210120221 is 12202101212.

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 21210120221 - 2⁶ = 21210120157 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21210120196 and 21210120205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210120271) 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, 42250985 + ... + 42251486.

It is an arithmetic number, because the mean of its divisors is an integer number (5323655736).

Almost surely, 2^21210120221 is an apocalyptic number.

It is an amenable number.

21210120221 is a deficient number, since it is larger than the sum of its proper divisors (84502723).

21210120221 is an equidigital number, since it uses as much as digits as its factorization.

21210120221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84502722.

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

Adding to 21210120221 its reverse (12202101212), we get a palindrome (33412221433).

The spelling of 21210120221 in words is "twenty-one billion, two hundred ten million, one hundred twenty thousand, two hundred twenty-one".