1205415661 has 4 divisors (see below), whose sum is σ = 1211661532. Its totient is φ = 1199169792.

The previous prime is 1205415649. The next prime is 1205415667. The reversal of 1205415661 is 1665145021.

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

It can be written as a sum of positive squares in 2 ways, for example, as 888397636 + 317018025 = 29806^2 + 17805^2 .

It is a cyclic number.

It is not a de Polignac number, because 1205415661 - 2⁹ = 1205415149 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 (1205415667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3122646 + ... + 3123031.

It is an arithmetic number, because the mean of its divisors is an integer number (302915383).

Almost surely, 2^1205415661 is an apocalyptic number.

It is an amenable number.

1205415661 is a deficient number, since it is larger than the sum of its proper divisors (6245871).

1205415661 is an equidigital number, since it uses as much as digits as its factorization.

1205415661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6245870.

The product of its (nonzero) digits is 7200, while the sum is 31.

The square root of 1205415661 is about 34719.0964888201. The cubic root of 1205415661 is about 1064.2547810374.

The spelling of 1205415661 in words is "one billion, two hundred five million, four hundred fifteen thousand, six hundred sixty-one".