21221001001 has 2 divisors, whose sum is σ = 21221001002. Its totient is φ = 21221001000.

The previous prime is 21221000987. The next prime is 21221001007. The reversal of 21221001001 is 10010012212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21165885225 + 55115776 = 145485^2 + 7424^2 .

It is a cyclic number.

It is not a de Polignac number, because 21221001001 - 2¹³ = 21220992809 is a prime.

It is not a weakly prime, because it can be changed into another prime (21221001007) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610500500 + 10610500501.

It is an arithmetic number, because the mean of its divisors is an integer number (10610500501).

Almost surely, 2^21221001001 is an apocalyptic number.

It is an amenable number.

21221001001 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221001001 is an equidigital number, since it uses as much as digits as its factorization.

21221001001 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 21221001001 its reverse (10010012212), we get a palindrome (31231013213).

The spelling of 21221001001 in words is "twenty-one billion, two hundred twenty-one million, one thousand, one".