21001012100 has 36 divisors (see below), whose sum is σ = 45931060224. Its totient is φ = 8334254880.

The previous prime is 21001012079. The next prime is 21001012129. The reversal of 21001012100 is 121010012.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 814112 + ... + 839511.

It is an arithmetic number, because the mean of its divisors is an integer number (1275862784).

Almost surely, 2^21001012100 is an apocalyptic number.

21001012100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21001012100 is an abundant number, since it is smaller than the sum of its proper divisors (24930048124).

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

21001012100 is a wasteful number, since it uses less digits than its factorization.

21001012100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1653764 (or 1653757 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 8.

Adding to 21001012100 its reverse (121010012), we get a palindrome (21122022112).

The spelling of 21001012100 in words is "twenty-one billion, one million, twelve thousand, one hundred".