21002020021001 has 2 divisors, whose sum is σ = 21002020021002. Its totient is φ = 21002020021000.

The previous prime is 21002020020983. The next prime is 21002020021033. The reversal of 21002020021001 is 10012002020012.

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., 13280157198025 + 7721862822976 = 3644195^2 + 2778824^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21002020021001 is a prime.

It is not a weakly prime, because it can be changed into another prime (21002020021061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501010010500 + 10501010010501.

It is an arithmetic number, because the mean of its divisors is an integer number (10501010010501).

Almost surely, 2^{21002020021001} is an apocalyptic number.

It is an amenable number.

21002020021001 is a deficient number, since it is larger than the sum of its proper divisors (1).

21002020021001 is an equidigital number, since it uses as much as digits as its factorization.

21002020021001 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 21002020021001 its reverse (10012002020012), we get a palindrome (31014022041013).

The spelling of 21002020021001 in words is "twenty-one trillion, two billion, twenty million, twenty-one thousand, one".