21001212017 has 2 divisors, whose sum is σ = 21001212018. Its totient is φ = 21001212016.

The previous prime is 21001212007. The next prime is 21001212047. The reversal of 21001212017 is 71021210012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11422479376 + 9578732641 = 106876^2 + 97871^2 .

It is a cyclic number.

It is not a de Polignac number, because 21001212017 - 2⁸ = 21001211761 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21001211986 and 21001212004.

It is not a weakly prime, because it can be changed into another prime (21001212007) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500606008 + 10500606009.

It is an arithmetic number, because the mean of its divisors is an integer number (10500606009).

Almost surely, 2^21001212017 is an apocalyptic number.

It is an amenable number.

21001212017 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001212017 is an equidigital number, since it uses as much as digits as its factorization.

21001212017 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 56, while the sum is 17.

Adding to 21001212017 its reverse (71021210012), we get a palindrome (92022422029).

The spelling of 21001212017 in words is "twenty-one billion, one million, two hundred twelve thousand, seventeen".