1266563988 has 36 divisors (see below), whose sum is σ = 3389922900. Its totient is φ = 397353216.

The previous prime is 1266563933. The next prime is 1266563989. The reversal of 1266563988 is 8893656621.

It is a happy number.

1266563988 is a `hidden beast` number, since 12 + 66 + 563 + 9 + 8 + 8 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 1114090884 + 152473104 = 33378^2 + 12348^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1266563989) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1034163 + ... + 1035386.

It is an arithmetic number, because the mean of its divisors is an integer number (94164525).

Almost surely, 2^1266563988 is an apocalyptic number.

1266563988 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

1266563988 is an abundant number, since it is smaller than the sum of its proper divisors (2123358912).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1266563988 is a wasteful number, since it uses less digits than its factorization.

1266563988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2069576 (or 2069571 counting only the distinct ones).

The product of its digits is 3732480, while the sum is 54.

The square root of 1266563988 is about 35588.8183001347. The cubic root of 1266563988 is about 1081.9546187701.

The spelling of 1266563988 in words is "one billion, two hundred sixty-six million, five hundred sixty-three thousand, nine hundred eighty-eight".