1205306561 has 16 divisors (see below), whose sum is σ = 1270926720. Its totient is φ = 1141557120.

The previous prime is 1205306551. The next prime is 1205306563. The reversal of 1205306561 is 1656035021.

It is a cyclic number.

It is not a de Polignac number, because 1205306561 - 2¹⁰ = 1205305537 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1205306563) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1272290 + ... + 1273236.

It is an arithmetic number, because the mean of its divisors is an integer number (79432920).

Almost surely, 2^1205306561 is an apocalyptic number.

It is an amenable number.

1205306561 is a deficient number, since it is larger than the sum of its proper divisors (65620159).

1205306561 is an equidigital number, since it uses as much as digits as its factorization.

1205306561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1864.

The product of its (nonzero) digits is 5400, while the sum is 29.

The square root of 1205306561 is about 34717.5252718278. The cubic root of 1205306561 is about 1064.2226721410. Note that the first 3 decimals are identical.

The spelling of 1205306561 in words is "one billion, two hundred five million, three hundred six thousand, five hundred sixty-one".