21021111100 has 72 divisors (see below), whose sum is σ = 51478736400. Its totient is φ = 7380441600.

The previous prime is 21021111049. The next prime is 21021111131. The reversal of 21021111100 is 111112012.

It is a super-2 number, since 2×21021111100² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a congruent number.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 297585 + ... + 361384.

It is an arithmetic number, because the mean of its divisors is an integer number (714982450).

Almost surely, 2^21021111100 is an apocalyptic number.

21021111100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21021111100 is an abundant number, since it is smaller than the sum of its proper divisors (30457625300).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21021111100 is a wasteful number, since it uses less digits than its factorization.

21021111100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 659023 (or 659016 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 10.

Adding to 21021111100 its reverse (111112012), we get a palindrome (21132223112).

The spelling of 21021111100 in words is "twenty-one billion, twenty-one million, one hundred eleven thousand, one hundred".