1264205665 has 8 divisors (see below), whose sum is σ = 1521051840. Its totient is φ = 1008694512.

The previous prime is 1264205651. The next prime is 1264205681. The reversal of 1264205665 is 5665024621.

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 1264205665 - 2²¹ = 1262108513 is a prime.

It is an unprimeable number.

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, 331669 + ... + 335458.

It is an arithmetic number, because the mean of its divisors is an integer number (190131480).

Almost surely, 2^1264205665 is an apocalyptic number.

It is an amenable number.

1264205665 is a deficient number, since it is larger than the sum of its proper divisors (256846175).

1264205665 is an equidigital number, since it uses as much as digits as its factorization.

1264205665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 667511.

The product of its (nonzero) digits is 86400, while the sum is 37.

The square root of 1264205665 is about 35555.6699416563. The cubic root of 1264205665 is about 1081.2826738319.

The spelling of 1264205665 in words is "one billion, two hundred sixty-four million, two hundred five thousand, six hundred sixty-five".