1266557565 has 64 divisors (see below), whose sum is σ = 2499840000. Its totient is φ = 533240064.

The previous prime is 1266557557. The next prime is 1266557581. The reversal of 1266557565 is 5657556621.

It is a happy number.

It is not a de Polignac number, because 1266557565 - 2³ = 1266557557 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 844186 + ... + 845684.

It is an arithmetic number, because the mean of its divisors is an integer number (39060000).

Almost surely, 2^1266557565 is an apocalyptic number.

1266557565 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1266557565 is a deficient number, since it is larger than the sum of its proper divisors (1233282435).

1266557565 is a wasteful number, since it uses less digits than its factorization.

1266557565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2146.

The product of its digits is 1890000, while the sum is 48.

The square root of 1266557565 is about 35588.7280610027. The cubic root of 1266557565 is about 1081.9527898307.

The spelling of 1266557565 in words is "one billion, two hundred sixty-six million, five hundred fifty-seven thousand, five hundred sixty-five".