21002112100 has 18 divisors (see below), whose sum is σ = 45574583474. Its totient is φ = 8400844800.

The previous prime is 21002112067. The next prime is 21002112101. The reversal of 21002112100 is 121120012.

It can be written as a sum of positive squares in 3 ways, for example, as 7145997156 + 13856114944 = 84534^2 + 117712^2 .

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

It is not an unprimeable number, because it can be changed into a prime (21002112101) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 105010461 + ... + 105010660.

Almost surely, 2^21002112100 is an apocalyptic number.

21002112100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21002112100 is an abundant number, since it is smaller than the sum of its proper divisors (24572471374).

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

21002112100 is a wasteful number, since it uses less digits than its factorization.

21002112100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 210021135 (or 210021128 counting only the distinct ones).

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

Adding to 21002112100 its reverse (121120012), we get a palindrome (21123232112).

The spelling of 21002112100 in words is "twenty-one billion, two million, one hundred twelve thousand, one hundred".