21021011100 has 108 divisors (see below), whose sum is σ = 65926702296. Its totient is φ = 5602412160.

The previous prime is 21021011087. The next prime is 21021011101. The reversal of 21021011100 is 111012012.

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 (21021011101) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 1869094 + ... + 1880306.

Almost surely, 2^21021011100 is an apocalyptic number.

21021011100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21021011100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32963351148).

21021011100 is an abundant number, since it is smaller than the sum of its proper divisors (44905691196).

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

21021011100 is a wasteful number, since it uses less digits than its factorization.

21021011100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13316 (or 13306 counting only the distinct ones).

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

Adding to 21021011100 its reverse (111012012), we get a palindrome (21132023112).

The spelling of 21021011100 in words is "twenty-one billion, twenty-one million, eleven thousand, one hundred".