1278921911 has 2 divisors, whose sum is σ = 1278921912. Its totient is φ = 1278921910.

The previous prime is 1278921881. The next prime is 1278921949. The reversal of 1278921911 is 1191298721.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1278921911 - 2¹⁰ = 1278920887 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1278921971) 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, 639460955 + 639460956.

It is an arithmetic number, because the mean of its divisors is an integer number (639460956).

Almost surely, 2^1278921911 is an apocalyptic number.

1278921911 is a deficient number, since it is larger than the sum of its proper divisors (1).

1278921911 is an equidigital number, since it uses as much as digits as its factorization.

1278921911 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18144, while the sum is 41.

The square root of 1278921911 is about 35762.0177143293. The cubic root of 1278921911 is about 1085.4621293726.

The spelling of 1278921911 in words is "one billion, two hundred seventy-eight million, nine hundred twenty-one thousand, nine hundred eleven".