21000221100021 has 4 divisors (see below), whose sum is σ = 28000294800032. Its totient is φ = 14000147400012.

The previous prime is 21000221099989. The next prime is 21000221100137. The reversal of 21000221100021 is 12000112200012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21000221100021 - 2⁵ = 21000221099989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000221100821) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3500036850001 + ... + 3500036850006.

It is an arithmetic number, because the mean of its divisors is an integer number (7000073700008).

Almost surely, 2^{21000221100021} is an apocalyptic number.

It is an amenable number.

21000221100021 is a deficient number, since it is larger than the sum of its proper divisors (7000073700011).

21000221100021 is an equidigital number, since it uses as much as digits as its factorization.

21000221100021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7000073700010.

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21000221100021 its reverse (12000112200012), we get a palindrome (33000333300033).

The spelling of 21000221100021 in words is "twenty-one trillion, two hundred twenty-one million, one hundred thousand, twenty-one".