7843005661 has 4 divisors (see below), whose sum is σ = 8034298524. Its totient is φ = 7651712800.

The previous prime is 7843005619. The next prime is 7843005671. The reversal of 7843005661 is 1665003487.

It is a happy number.

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 988159225 + 6854846436 = 31435^2 + 82794^2 .

It is a cyclic number.

It is not a de Polignac number, because 7843005661 - 2²³ = 7834617053 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7843005671) 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, 95646370 + ... + 95646451.

It is an arithmetic number, because the mean of its divisors is an integer number (2008574631).

Almost surely, 2^7843005661 is an apocalyptic number.

It is an amenable number.

7843005661 is a deficient number, since it is larger than the sum of its proper divisors (191292863).

7843005661 is a wasteful number, since it uses less digits than its factorization.

7843005661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 191292862.

The product of its (nonzero) digits is 120960, while the sum is 40.

The square root of 7843005661 is about 88560.7455987132. The cubic root of 7843005661 is about 1986.8306123649.

The spelling of 7843005661 in words is "seven billion, eight hundred forty-three million, five thousand, six hundred sixty-one".