1256820667 has 2 divisors, whose sum is σ = 1256820668. Its totient is φ = 1256820666.

The previous prime is 1256820661. The next prime is 1256820689. The reversal of 1256820667 is 7660286521.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1256820667 is a prime.

It is not a weakly prime, because it can be changed into another prime (1256820661) 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, 628410333 + 628410334.

It is an arithmetic number, because the mean of its divisors is an integer number (628410334).

Almost surely, 2^1256820667 is an apocalyptic number.

1256820667 is a deficient number, since it is larger than the sum of its proper divisors (1).

1256820667 is an equidigital number, since it uses as much as digits as its factorization.

1256820667 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 241920, while the sum is 43.

The square root of 1256820667 is about 35451.6666321909. Note that the first 4 decimals coincide. The cubic root of 1256820667 is about 1079.1730830134.

The spelling of 1256820667 in words is "one billion, two hundred fifty-six million, eight hundred twenty thousand, six hundred sixty-seven".