1243242661 has 4 divisors (see below), whose sum is σ = 1276843852. Its totient is φ = 1209641472.

The previous prime is 1243242653. The next prime is 1243242683. The reversal of 1243242661 is 1662423421.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1662423421 = 17 ⋅97789613.

It can be written as a sum of positive squares in 2 ways, for example, as 888636100 + 354606561 = 29810^2 + 18831^2 .

It is a cyclic number.

It is not a de Polignac number, because 1243242661 - 2³ = 1243242653 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 (1243242601) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16800540 + ... + 16800613.

It is an arithmetic number, because the mean of its divisors is an integer number (319210963).

Almost surely, 2^1243242661 is an apocalyptic number.

It is an amenable number.

1243242661 is a deficient number, since it is larger than the sum of its proper divisors (33601191).

1243242661 is an equidigital number, since it uses as much as digits as its factorization.

1243242661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33601190.

The product of its digits is 13824, while the sum is 31.

The square root of 1243242661 is about 35259.6463538703. The cubic root of 1243242661 is about 1075.2727372882.

The spelling of 1243242661 in words is "one billion, two hundred forty-three million, two hundred forty-two thousand, six hundred sixty-one".