66656660646 has 32 divisors (see below), whose sum is σ = 141194220768. Its totient is φ = 20906124800.

The previous prime is 66656660633. The next prime is 66656660659. The reversal of 66656660646 is 64606665666.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (66656660633) and next prime (66656660659).

It is a super-2 number, since 2×66656660646² (a number of 22 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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 in 15 ways as a sum of consecutive naturals, for example, 289216 + ... + 465788.

It is an arithmetic number, because the mean of its divisors is an integer number (4412319399).

Almost surely, 2^66656660646 is an apocalyptic number.

66656660646 is an abundant number, since it is smaller than the sum of its proper divisors (74537560122).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

66656660646 is a wasteful number, since it uses less digits than its factorization.

66656660646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 180296.

The product of its (nonzero) digits is 33592320, while the sum is 57.

The spelling of 66656660646 in words is "sixty-six billion, six hundred fifty-six million, six hundred sixty thousand, six hundred forty-six".