21102012100 has 72 divisors (see below), whose sum is σ = 49421697920. Its totient is φ = 7774462080.

The previous prime is 21102012037. The next prime is 21102012131. The reversal of 21102012100 is 121020112.

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

It is an unprimeable number.

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, 584371 + ... + 619429.

Almost surely, 2^21102012100 is an apocalyptic number.

21102012100 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 21102012100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24710848960).

21102012100 is an abundant number, since it is smaller than the sum of its proper divisors (28319685820).

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

21102012100 is a wasteful number, since it uses less digits than its factorization.

21102012100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35549 (or 35542 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 21102012100 its reverse (121020112), we get a palindrome (21223032212).

The spelling of 21102012100 in words is "twenty-one billion, one hundred two million, twelve thousand, one hundred".