21000120011 has 4 divisors (see below), whose sum is σ = 22615513872. Its totient is φ = 19384726152.

The previous prime is 21000119999. The next prime is 21000120013. The reversal of 21000120011 is 11002100012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21000120011 - 2¹⁸ = 20999857867 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21000120013) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 807696911 + ... + 807696936.

It is an arithmetic number, because the mean of its divisors is an integer number (5653878468).

Almost surely, 2^21000120011 is an apocalyptic number.

21000120011 is a deficient number, since it is larger than the sum of its proper divisors (1615393861).

21000120011 is a wasteful number, since it uses less digits than its factorization.

21000120011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1615393860.

The product of its (nonzero) digits is 4, while the sum is 8.

Adding to 21000120011 its reverse (11002100012), we get a palindrome (32002220023).

The spelling of 21000120011 in words is "twenty-one billion, one hundred twenty thousand, eleven".