21011012221021 has 4 divisors (see below), whose sum is σ = 21011116295772. Its totient is φ = 21010908146272.

The previous prime is 21011012220983. The next prime is 21011012221033. The reversal of 21011012221021 is 12012221011012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 19067806888900 + 1943205332121 = 4366670^2 + 1393989^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011012221021 - 2¹⁹ = 21011011696733 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21011012220986 and 21011012221004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011012221621) 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, 51733960 + ... + 52138513.

It is an arithmetic number, because the mean of its divisors is an integer number (5252779073943).

Almost surely, 2^{21011012221021} is an apocalyptic number.

It is an amenable number.

21011012221021 is a deficient number, since it is larger than the sum of its proper divisors (104074751).

21011012221021 is a wasteful number, since it uses less digits than its factorization.

21011012221021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 104074750.

The product of its (nonzero) digits is 32, while the sum is 16.

Adding to 21011012221021 its reverse (12012221011012), we get a palindrome (33023233232033).

The spelling of 21011012221021 in words is "twenty-one trillion, eleven billion, twelve million, two hundred twenty-one thousand, twenty-one".