21000100002021 has 96 divisors (see below), whose sum is σ = 37403125760000. Its totient is φ = 11317488430752.

The previous prime is 21000100001893. The next prime is 21000100002053. The reversal of 21000100002021 is 12020000100012.

It is not a de Polignac number, because 21000100002021 - 2⁷ = 21000100001893 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 = 21000100001994 and 21000100002012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000100000021) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 12276840 + ... + 13882398.

Almost surely, 2^{21000100002021} is an apocalyptic number.

21000100002021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21000100002021 is a deficient number, since it is larger than the sum of its proper divisors (16403025757979).

21000100002021 is a wasteful number, since it uses less digits than its factorization.

21000100002021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1605828 (or 1605811 counting only the distinct ones).

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

Adding to 21000100002021 its reverse (12020000100012), we get a palindrome (33020100102033).

The spelling of 21000100002021 in words is "twenty-one trillion, one hundred million, two thousand, twenty-one".