21000021110021 has 16 divisors (see below), whose sum is σ = 22315894191360. Its totient is φ = 19693220413440.

The previous prime is 21000021109901. The next prime is 21000021110023. The reversal of 21000021110021 is 12001112000012.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21000021110021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21000021109984 and 21000021110011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000021110023) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3770930 + ... + 7497996.

It is an arithmetic number, because the mean of its divisors is an integer number (1394743386960).

Almost surely, 2^{21000021110021} is an apocalyptic number.

It is an amenable number.

21000021110021 is a deficient number, since it is larger than the sum of its proper divisors (1315873081339).

21000021110021 is a wasteful number, since it uses less digits than its factorization.

21000021110021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3728284.

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 21000021110021 its reverse (12001112000012), we get a palindrome (33001133110033).

The spelling of 21000021110021 in words is "twenty-one trillion, twenty-one million, one hundred ten thousand, twenty-one".