21120102100 has 36 divisors (see below), whose sum is σ = 45877743324. Its totient is φ = 8439354880.

The previous prime is 21120102089. The next prime is 21120102109. The reversal of 21120102100 is 120102112.

It can be written as a sum of positive squares in 6 ways, for example, as 21958596 + 21098143504 = 4686^2 + 145252^2 .

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21120102109) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10387 + ... + 205786.

It is an arithmetic number, because the mean of its divisors is an integer number (1274381759).

Almost surely, 2^21120102100 is an apocalyptic number.

21120102100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21120102100 is an abundant number, since it is smaller than the sum of its proper divisors (24757641224).

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

21120102100 is a wasteful number, since it uses less digits than its factorization.

21120102100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 217164 (or 217157 counting only the distinct ones).

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

Adding to 21120102100 its reverse (120102112), we get a palindrome (21240204212).

The spelling of 21120102100 in words is "twenty-one billion, one hundred twenty million, one hundred two thousand, one hundred".