1266216521 has 2 divisors, whose sum is σ = 1266216522. Its totient is φ = 1266216520.

The previous prime is 1266216499. The next prime is 1266216527. The reversal of 1266216521 is 1256126621.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1086361600 + 179854921 = 32960^2 + 13411^2 .

It is a cyclic number.

It is not a de Polignac number, because 1266216521 - 2¹⁰ = 1266215497 is a prime.

It is not a weakly prime, because it can be changed into another prime (1266216527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 633108260 + 633108261.

It is an arithmetic number, because the mean of its divisors is an integer number (633108261).

Almost surely, 2^1266216521 is an apocalyptic number.

It is an amenable number.

1266216521 is a deficient number, since it is larger than the sum of its proper divisors (1).

1266216521 is an equidigital number, since it uses as much as digits as its factorization.

1266216521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8640, while the sum is 32.

The square root of 1266216521 is about 35583.9362774834. The cubic root of 1266216521 is about 1081.8556691940.

The spelling of 1266216521 in words is "one billion, two hundred sixty-six million, two hundred sixteen thousand, five hundred twenty-one".