21010022021921 has 2 divisors, whose sum is σ = 21010022021922. Its totient is φ = 21010022021920.

The previous prime is 21010022021917. The next prime is 21010022021929. The reversal of 21010022021921 is 12912022001012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20421903283600 + 588118738321 = 4519060^2 + 766889^2 .

It is a cyclic number.

It is not a de Polignac number, because 21010022021921 - 2² = 21010022021917 is a prime.

It is not a weakly prime, because it can be changed into another prime (21010022021929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505011010960 + 10505011010961.

It is an arithmetic number, because the mean of its divisors is an integer number (10505011010961).

Almost surely, 2^{21010022021921} is an apocalyptic number.

It is an amenable number.

21010022021921 is a deficient number, since it is larger than the sum of its proper divisors (1).

21010022021921 is an equidigital number, since it uses as much as digits as its factorization.

21010022021921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 288, while the sum is 23.

Adding to 21010022021921 its reverse (12912022001012), we get a palindrome (33922044022933).

The spelling of 21010022021921 in words is "twenty-one trillion, ten billion, twenty-two million, twenty-one thousand, nine hundred twenty-one".