21100002021 has 24 divisors (see below), whose sum is σ = 34889961600. Its totient is φ = 12036993696.

The previous prime is 21100001929. The next prime is 21100002041. The reversal of 21100002021 is 12020000112.

It is not a de Polignac number, because 21100002021 - 2⁷ = 21100001893 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 21100001994 and 21100002012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21100002041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 241830 + ... + 317303.

It is an arithmetic number, because the mean of its divisors is an integer number (1453748400).

Almost surely, 2^21100002021 is an apocalyptic number.

21100002021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21100002021 is a deficient number, since it is larger than the sum of its proper divisors (13789959579).

21100002021 is a wasteful number, since it uses less digits than its factorization.

21100002021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 559745 (or 559742 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

Adding to 21100002021 its reverse (12020000112), we get a palindrome (33120002133).

The spelling of 21100002021 in words is "twenty-one billion, one hundred million, two thousand, twenty-one".