66355661 has 4 divisors (see below), whose sum is σ = 67346112. Its totient is φ = 65365212.

The previous prime is 66355643. The next prime is 66355693. The reversal of 66355661 is 16655366.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66355661 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66355631) 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, 495125 + ... + 495258.

It is an arithmetic number, because the mean of its divisors is an integer number (16836528).

Almost surely, 2^66355661 is an apocalyptic number.

It is an amenable number.

66355661 is a deficient number, since it is larger than the sum of its proper divisors (990451).

66355661 is an equidigital number, since it uses as much as digits as its factorization.

66355661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 990450.

The product of its digits is 97200, while the sum is 38.

The square root of 66355661 is about 8145.8984157673. The cubic root of 66355661 is about 404.8486168968.

The spelling of 66355661 in words is "sixty-six million, three hundred fifty-five thousand, six hundred sixty-one".