1261566499 has 2 divisors, whose sum is σ = 1261566500. Its totient is φ = 1261566498.

The previous prime is 1261566443. The next prime is 1261566521. The reversal of 1261566499 is 9946651621.

It is a strong prime.

It is an emirp because it is prime and its reverse (9946651621) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1261566499 - 2¹⁵ = 1261533731 is a prime.

It is not a weakly prime, because it can be changed into another prime (1261569499) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 630783249 + 630783250.

It is an arithmetic number, because the mean of its divisors is an integer number (630783250).

Almost surely, 2^1261566499 is an apocalyptic number.

1261566499 is a deficient number, since it is larger than the sum of its proper divisors (1).

1261566499 is an equidigital number, since it uses as much as digits as its factorization.

1261566499 is an evil number, because the sum of its binary digits is even.

The product of its digits is 699840, while the sum is 49.

The square root of 1261566499 is about 35518.5373995045. The cubic root of 1261566499 is about 1080.5297181365.

The spelling of 1261566499 in words is "one billion, two hundred sixty-one million, five hundred sixty-six thousand, four hundred ninety-nine".