66216372757 has 4 divisors (see below), whose sum is σ = 67204676896. Its totient is φ = 65228068620.

The previous prime is 66216372749. The next prime is 66216372773. The reversal of 66216372757 is 75727361266.

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, and also an emirpimes, since its reverse is a distinct semiprime: 75727361266 = 2 ⋅37863680633.

It is a cyclic number.

It is not a de Polignac number, because 66216372757 - 2³ = 66216372749 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66216372457) 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, 494151969 + ... + 494152102.

It is an arithmetic number, because the mean of its divisors is an integer number (16801169224).

Almost surely, 2^66216372757 is an apocalyptic number.

66216372757 is a gapful number since it is divisible by the number (67) formed by its first and last digit.

It is an amenable number.

66216372757 is a deficient number, since it is larger than the sum of its proper divisors (988304139).

66216372757 is an equidigital number, since it uses as much as digits as its factorization.

66216372757 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 988304138.

The product of its digits is 4445280, while the sum is 52.

The spelling of 66216372757 in words is "sixty-six billion, two hundred sixteen million, three hundred seventy-two thousand, seven hundred fifty-seven".