1205661611 has 24 divisors (see below), whose sum is σ = 1539503424. Its totient is φ = 933644880.

The previous prime is 1205661601. The next prime is 1205661617. The reversal of 1205661611 is 1161665021.

It is not a de Polignac number, because 1205661611 - 2⁶ = 1205661547 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1205661617) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 80996 + ... + 94718.

It is an arithmetic number, because the mean of its divisors is an integer number (64145976).

Almost surely, 2^1205661611 is an apocalyptic number.

1205661611 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1205661611 is a deficient number, since it is larger than the sum of its proper divisors (333841813).

1205661611 is a wasteful number, since it uses less digits than its factorization.

1205661611 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13911 (or 13904 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 29.

The square root of 1205661611 is about 34722.6383070181. The cubic root of 1205661611 is about 1064.3271587439.

The spelling of 1205661611 in words is "one billion, two hundred five million, six hundred sixty-one thousand, six hundred eleven".