21012001273 has 2 divisors, whose sum is σ = 21012001274. Its totient is φ = 21012001272.

The previous prime is 21012001259. The next prime is 21012001291. The reversal of 21012001273 is 37210021012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20584214784 + 427786489 = 143472^2 + 20683^2 .

It is a cyclic number.

It is not a de Polignac number, because 21012001273 - 2⁹ = 21012000761 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21012001273.

It is not a weakly prime, because it can be changed into another prime (21012001573) 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, 10506000636 + 10506000637.

It is an arithmetic number, because the mean of its divisors is an integer number (10506000637).

Almost surely, 2^21012001273 is an apocalyptic number.

It is an amenable number.

21012001273 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012001273 is an equidigital number, since it uses as much as digits as its factorization.

21012001273 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 168, while the sum is 19.

Adding to 21012001273 its reverse (37210021012), we get a palindrome (58222022285).

The spelling of 21012001273 in words is "twenty-one billion, twelve million, one thousand, two hundred seventy-three".