21001221001211 has 16 divisors (see below), whose sum is σ = 22917199850496. Its totient is φ = 19086372540000.

The previous prime is 21001221001207. The next prime is 21001221001213. The reversal of 21001221001211 is 11210012210012.

It is a cyclic number.

It is not a de Polignac number, because 21001221001211 - 2² = 21001221001207 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21001221001213) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 807074381 + ... + 807100401.

It is an arithmetic number, because the mean of its divisors is an integer number (1432324990656).

Almost surely, 2^{21001221001211} is an apocalyptic number.

21001221001211 is a deficient number, since it is larger than the sum of its proper divisors (1915978849285).

21001221001211 is a wasteful number, since it uses less digits than its factorization.

21001221001211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44914.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21001221001211 its reverse (11210012210012), we get a palindrome (32211233211223).

It can be divided in two parts, 210012210012 and 11, that multiplied together give a palindrome (2310134310132).

The spelling of 21001221001211 in words is "twenty-one trillion, one billion, two hundred twenty-one million, one thousand, two hundred eleven".