21011121200021 has 8 divisors (see below), whose sum is σ = 21499435390680. Its totient is φ = 20526209896192.

The previous prime is 21011121199973. The next prime is 21011121200081. The reversal of 21011121200021 is 12000212111012.

It can be written as a sum of positive squares in 4 ways, for example, as 1031016852100 + 19980104347921 = 1015390^2 + 4469911^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21011121200021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21011121199969 and 21011121200005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011121200081) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 850709216 + ... + 850733913.

It is an arithmetic number, because the mean of its divisors is an integer number (2687429423835).

Almost surely, 2^{21011121200021} is an apocalyptic number.

It is an amenable number.

21011121200021 is a deficient number, since it is larger than the sum of its proper divisors (488314190659).

21011121200021 is a wasteful number, since it uses less digits than its factorization.

21011121200021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1701443415.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21011121200021 its reverse (12000212111012), we get a palindrome (33011333311033).

The spelling of 21011121200021 in words is "twenty-one trillion, eleven billion, one hundred twenty-one million, two hundred thousand, twenty-one".