11651565601661 has 2 divisors, whose sum is σ = 11651565601662. Its totient is φ = 11651565601660.

The previous prime is 11651565601639. The next prime is 11651565601681. The reversal of 11651565601661 is 16610656515611.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11651538499225 + 27102436 = 3413435^2 + 5206^2 .

It is a cyclic number.

It is not a de Polignac number, because 11651565601661 - 2¹⁸ = 11651565339517 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (11651565601681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5825782800830 + 5825782800831.

It is an arithmetic number, because the mean of its divisors is an integer number (5825782800831).

Almost surely, 2^{11651565601661} is an apocalyptic number.

It is an amenable number.

11651565601661 is a deficient number, since it is larger than the sum of its proper divisors (1).

11651565601661 is an equidigital number, since it uses as much as digits as its factorization.

11651565601661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 972000, while the sum is 50.

The spelling of 11651565601661 in words is "eleven trillion, six hundred fifty-one billion, five hundred sixty-five million, six hundred one thousand, six hundred sixty-one".