21001220421111 has 12 divisors (see below), whose sum is σ = 34668681330192. Its totient is φ = 12000697383456.

The previous prime is 21001220421067. The next prime is 21001220421113. The reversal of 21001220421111 is 11112402210012.

21001220421111 is a `hidden beast` number, since 2 + 10 + 0 + 1 + 220 + 421 + 1 + 11 = 666.

It is not a de Polignac number, because 21001220421111 - 2⁹ = 21001220420599 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001220421113) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 166676352486 + ... + 166676352611.

It is an arithmetic number, because the mean of its divisors is an integer number (2889056777516).

Almost surely, 2^{21001220421111} is an apocalyptic number.

21001220421111 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21001220421111 is a deficient number, since it is larger than the sum of its proper divisors (13667460909081).

21001220421111 is a wasteful number, since it uses less digits than its factorization.

21001220421111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 333352705110 (or 333352705107 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 18.

Adding to 21001220421111 its reverse (11112402210012), we get a palindrome (32113622631123).

The spelling of 21001220421111 in words is "twenty-one trillion, one billion, two hundred twenty million, four hundred twenty-one thousand, one hundred eleven".