21001002220021 has 2 divisors, whose sum is σ = 21001002220022. Its totient is φ = 21001002220020.

The previous prime is 21001002219997. The next prime is 21001002220049. The reversal of 21001002220021 is 12002220010012.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16935076800625 + 4065925419396 = 4115225^2 + 2016414^2 .

It is a cyclic number.

It is not a de Polignac number, because 21001002220021 - 2¹¹ = 21001002217973 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21001002219983 and 21001002220010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21001002220091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500501110010 + 10500501110011.

It is an arithmetic number, because the mean of its divisors is an integer number (10500501110011).

Almost surely, 2^{21001002220021} is an apocalyptic number.

It is an amenable number.

21001002220021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001002220021 is an equidigital number, since it uses as much as digits as its factorization.

21001002220021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32, while the sum is 13.

Adding to 21001002220021 its reverse (12002220010012), we get a palindrome (33003222230033).

The spelling of 21001002220021 in words is "twenty-one trillion, one billion, two million, two hundred twenty thousand, twenty-one".