7865775661 has 2 divisors, whose sum is σ = 7865775662. Its totient is φ = 7865775660.

The previous prime is 7865775653. The next prime is 7865775707. The reversal of 7865775661 is 1665775687.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5257120036 + 2608655625 = 72506^2 + 51075^2 .

It is a cyclic number.

It is not a de Polignac number, because 7865775661 - 2³ = 7865775653 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 7865775596 and 7865775605.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7865775641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3932887830 + 3932887831.

It is an arithmetic number, because the mean of its divisors is an integer number (3932887831).

Almost surely, 2^7865775661 is an apocalyptic number.

It is an amenable number.

7865775661 is a deficient number, since it is larger than the sum of its proper divisors (1).

7865775661 is an equidigital number, since it uses as much as digits as its factorization.

7865775661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14817600, while the sum is 58.

The square root of 7865775661 is about 88689.2082555708. The cubic root of 7865775661 is about 1988.7514925620.

The spelling of 7865775661 in words is "seven billion, eight hundred sixty-five million, seven hundred seventy-five thousand, six hundred sixty-one".