21100020111 has 24 divisors (see below), whose sum is σ = 31073777280. Its totient is φ = 13791974976.

The previous prime is 21100020107. The next prime is 21100020143. The reversal of 21100020111 is 11102000112.

It is a happy number.

It is not a de Polignac number, because 21100020111 - 2² = 21100020107 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 = 21100020093 and 21100020102.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21100020311) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 733345 + ... + 761573.

It is an arithmetic number, because the mean of its divisors is an integer number (1294740720).

Almost surely, 2^21100020111 is an apocalyptic number.

21100020111 is a deficient number, since it is larger than the sum of its proper divisors (9973757169).

21100020111 is a wasteful number, since it uses less digits than its factorization.

21100020111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29855 (or 29852 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

Adding to 21100020111 its reverse (11102000112), we get a palindrome (32202020223).

The spelling of 21100020111 in words is "twenty-one billion, one hundred million, twenty thousand, one hundred eleven".