21000221211 has 16 divisors (see below), whose sum is σ = 29078560800. Its totient is φ = 13464772608.

The previous prime is 21000221189. The next prime is 21000221243. The reversal of 21000221211 is 11212200012.

It is not a de Polignac number, because 21000221211 - 2⁹ = 21000220699 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21000221611) 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, 447256 + ... + 491973.

It is an arithmetic number, because the mean of its divisors is an integer number (1817410050).

Almost surely, 2^21000221211 is an apocalyptic number.

21000221211 is a deficient number, since it is larger than the sum of its proper divisors (8078339589).

21000221211 is a wasteful number, since it uses less digits than its factorization.

21000221211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 939518.

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21000221211 its reverse (11212200012), we get a palindrome (32212421223).

The spelling of 21000221211 in words is "twenty-one billion, two hundred twenty-one thousand, two hundred eleven".