65661691 has 2 divisors, whose sum is σ = 65661692. Its totient is φ = 65661690.

The previous prime is 65661677. The next prime is 65661697. The reversal of 65661691 is 19616656.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 65661691 - 2¹⁵ = 65628923 is a prime.

It is a super-2 number, since 2×65661691² = 8622915329958962, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (65661697) 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 as a sum of consecutive naturals, namely, 32830845 + 32830846.

It is an arithmetic number, because the mean of its divisors is an integer number (32830846).

Almost surely, 2^65661691 is an apocalyptic number.

65661691 is a deficient number, since it is larger than the sum of its proper divisors (1).

65661691 is an equidigital number, since it uses as much as digits as its factorization.

65661691 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 58320, while the sum is 40.

The square root of 65661691 is about 8103.1901742462. The cubic root of 65661691 is about 403.4323199585.

The spelling of 65661691 in words is "sixty-five million, six hundred sixty-one thousand, six hundred ninety-one".