1261553728 has 28 divisors (see below), whose sum is σ = 2506748860. Its totient is φ = 629932032.

The previous prime is 1261553719. The next prime is 1261553747. The reversal of 1261553728 is 8273551621.

It can be written as a sum of positive squares in 2 ways, for example, as 470369344 + 791184384 = 21688^2 + 28128^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36400 + ... + 62032.

It is an arithmetic number, because the mean of its divisors is an integer number (89526745).

Almost surely, 2^1261553728 is an apocalyptic number.

It is an amenable number.

1261553728 is a deficient number, since it is larger than the sum of its proper divisors (1245195132).

1261553728 is an equidigital number, since it uses as much as digits as its factorization.

1261553728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26414 (or 26404 counting only the distinct ones).

The product of its digits is 100800, while the sum is 40.

The square root of 1261553728 is about 35518.3576196873. The cubic root of 1261553728 is about 1080.5260720104.

The spelling of 1261553728 in words is "one billion, two hundred sixty-one million, five hundred fifty-three thousand, seven hundred twenty-eight".