1261556885 has 8 divisors (see below), whose sum is σ = 1514453976. Its totient is φ = 1008855040.

The previous prime is 1261556861. The next prime is 1261556887. The reversal of 1261556885 is 5886551621.

It can be written as a sum of positive squares in 4 ways, for example, as 459930916 + 801625969 = 21446^2 + 28313^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1261556885 - 2¹⁶ = 1261491349 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261556887) 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, 34196 + ... + 60765.

It is an arithmetic number, because the mean of its divisors is an integer number (189306747).

Almost surely, 2^1261556885 is an apocalyptic number.

It is an amenable number.

1261556885 is a deficient number, since it is larger than the sum of its proper divisors (252897091).

1261556885 is an equidigital number, since it uses as much as digits as its factorization.

1261556885 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97623.

The product of its digits is 576000, while the sum is 47.

The square root of 1261556885 is about 35518.4020614667. The cubic root of 1261556885 is about 1080.5269733375.

The spelling of 1261556885 in words is "one billion, two hundred sixty-one million, five hundred fifty-six thousand, eight hundred eighty-five".