21010101111 has 32 divisors (see below), whose sum is σ = 32497920000. Its totient is φ = 13390100064.

The previous prime is 21010101097. The next prime is 21010101139. The reversal of 21010101111 is 11110101012.

It is not a de Polignac number, because 21010101111 - 2¹⁰ = 21010100087 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 21010101093 and 21010101102.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21010101191) 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 31 ways as a sum of consecutive naturals, for example, 1201650 + ... + 1219008.

It is an arithmetic number, because the mean of its divisors is an integer number (1015560000).

Almost surely, 2^21010101111 is an apocalyptic number.

21010101111 is a deficient number, since it is larger than the sum of its proper divisors (11487818889).

21010101111 is a wasteful number, since it uses less digits than its factorization.

21010101111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19340 (or 19334 counting only the distinct ones).

The product of its (nonzero) digits is 2, while the sum is 9.

Adding to 21010101111 its reverse (11110101012), we get a palindrome (32120202123).

Subtracting from 21010101111 its reverse (11110101012), we obtain a palindrome (9900000099).

The spelling of 21010101111 in words is "twenty-one billion, ten million, one hundred one thousand, one hundred eleven".