21102011100 has 54 divisors (see below), whose sum is σ = 66143084280. Its totient is φ = 5627202720.

The previous prime is 21102011081. The next prime is 21102011101. The reversal of 21102011100 is 111020112.

It is a happy number.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21102011101) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 11722440 + ... + 11724239.

Almost surely, 2^21102011100 is an apocalyptic number.

21102011100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21102011100 is an abundant number, since it is smaller than the sum of its proper divisors (45041073180).

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

21102011100 is a wasteful number, since it uses less digits than its factorization.

21102011100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23446699 (or 23446689 counting only the distinct ones).

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

Adding to 21102011100 its reverse (111020112), we get a palindrome (21213031212).

The spelling of 21102011100 in words is "twenty-one billion, one hundred two million, eleven thousand, one hundred".