21001021100 has 36 divisors (see below), whose sum is σ = 47970757800. Its totient is φ = 7958280960.

The previous prime is 21001021091. The next prime is 21001021103. The reversal of 21001021100 is 112010012.

It is not an unprimeable number, because it can be changed into a prime (21001021103) 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, 5524685 + ... + 5528484.

It is an arithmetic number, because the mean of its divisors is an integer number (1332521050).

Almost surely, 2^21001021100 is an apocalyptic number.

21001021100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21001021100 is an abundant number, since it is smaller than the sum of its proper divisors (26969736700).

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

21001021100 is a wasteful number, since it uses less digits than its factorization.

21001021100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11053202 (or 11053195 counting only the distinct ones).

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

Adding to 21001021100 its reverse (112010012), we get a palindrome (21113031112).

The spelling of 21001021100 in words is "twenty-one billion, one million, twenty-one thousand, one hundred".