1200661555 has 4 divisors (see below), whose sum is σ = 1440793872. Its totient is φ = 960529240.

The previous prime is 1200661549. The next prime is 1200661603. The reversal of 1200661555 is 5551660021.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 1200661555 - 2⁹ = 1200661043 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 120066151 + ... + 120066160.

It is an arithmetic number, because the mean of its divisors is an integer number (360198468).

Almost surely, 2^1200661555 is an apocalyptic number.

1200661555 is a deficient number, since it is larger than the sum of its proper divisors (240132317).

1200661555 is an equidigital number, since it uses as much as digits as its factorization.

1200661555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 240132316.

The product of its (nonzero) digits is 9000, while the sum is 31.

The square root of 1200661555 is about 34650.5635596306. The cubic root of 1200661555 is about 1062.8538130551.

It can be divided in two parts, 1200661 and 555, that added together give a square (1201216 = 1096²).

The spelling of 1200661555 in words is "one billion, two hundred million, six hundred sixty-one thousand, five hundred fifty-five".