1256666663 has 8 divisors (see below), whose sum is σ = 1498633728. Its totient is φ = 1030310424.

The previous prime is 1256666629. The next prime is 1256666689. The reversal of 1256666663 is 3666666521.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1256666663 - 2²² = 1252472359 is a prime.

It is a super-2 number, since 2×1256666663² = 3158422203791111138, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1256663663) 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 in 7 ways as a sum of consecutive naturals, for example, 3902531 + ... + 3902852.

It is an arithmetic number, because the mean of its divisors is an integer number (187329216).

Almost surely, 2^1256666663 is an apocalyptic number.

1256666663 is a deficient number, since it is larger than the sum of its proper divisors (241967065).

1256666663 is an equidigital number, since it uses as much as digits as its factorization.

1256666663 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7805413.

The product of its digits is 1399680, while the sum is 47.

The square root of 1256666663 is about 35449.4945380043. The cubic root of 1256666663 is about 1079.1290025372.

The spelling of 1256666663 in words is "one billion, two hundred fifty-six million, six hundred sixty-six thousand, six hundred sixty-three".