21212212221001 has 4 divisors (see below), whose sum is σ = 21528812403472. Its totient is φ = 20895612038532.

The previous prime is 21212212220999. The next prime is 21212212221073. The reversal of 21212212221001 is 10012221221212.

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 21212212221001 - 2¹ = 21212212220999 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21212212221001.

It is not an unprimeable number, because it can be changed into a prime (21212212221091) 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, 158300091135 + ... + 158300091268.

It is an arithmetic number, because the mean of its divisors is an integer number (5382203100868).

Almost surely, 2^{21212212221001} is an apocalyptic number.

It is an amenable number.

21212212221001 is a deficient number, since it is larger than the sum of its proper divisors (316600182471).

21212212221001 is an equidigital number, since it uses as much as digits as its factorization.

21212212221001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 316600182470.

The product of its (nonzero) digits is 128, while the sum is 19.

Adding to 21212212221001 its reverse (10012221221212), we get a palindrome (31224433442213).

The spelling of 21212212221001 in words is "twenty-one trillion, two hundred twelve billion, two hundred twelve million, two hundred twenty-one thousand, one".