1266531557 has 2 divisors, whose sum is σ = 1266531558. Its totient is φ = 1266531556.

The previous prime is 1266531551. The next prime is 1266531599. The reversal of 1266531557 is 7551356621.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 806900836 + 459630721 = 28406^2 + 21439^2 .

It is a cyclic number.

It is not a de Polignac number, because 1266531557 - 2²² = 1262337253 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1266531551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 633265778 + 633265779.

It is an arithmetic number, because the mean of its divisors is an integer number (633265779).

Almost surely, 2^1266531557 is an apocalyptic number.

It is an amenable number.

1266531557 is a deficient number, since it is larger than the sum of its proper divisors (1).

1266531557 is an equidigital number, since it uses as much as digits as its factorization.

1266531557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 189000, while the sum is 41.

The square root of 1266531557 is about 35588.3626625334. The cubic root of 1266531557 is about 1081.9453840295.

The spelling of 1266531557 in words is "one billion, two hundred sixty-six million, five hundred thirty-one thousand, five hundred fifty-seven".