1261798559 has 8 divisors (see below), whose sum is σ = 1471485600. Its totient is φ = 1081541328.

The previous prime is 1261798547. The next prime is 1261798583. The reversal of 1261798559 is 9558971621.

It is a happy number.

It is not a de Polignac number, because 1261798559 - 2⁴ = 1261798543 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1261798559.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261798589) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1839014 + ... + 1839699.

It is an arithmetic number, because the mean of its divisors is an integer number (183935700).

Almost surely, 2^1261798559 is an apocalyptic number.

1261798559 is a deficient number, since it is larger than the sum of its proper divisors (209687041).

1261798559 is an frugal number, since it uses more digits than its factorization.

1261798559 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3678734 (or 3678720 counting only the distinct ones).

The product of its digits is 1360800, while the sum is 53.

The square root of 1261798559 is about 35521.8039941667. The cubic root of 1261798559 is about 1080.5959670827.

The spelling of 1261798559 in words is "one billion, two hundred sixty-one million, seven hundred ninety-eight thousand, five hundred fifty-nine".