66641640 has 64 divisors (see below), whose sum is σ = 215308800. Its totient is φ = 16403712.

The previous prime is 66641639. The next prime is 66641657. The reversal of 66641640 is 4614666.

It is a super-2 number, since 2×66641640² = 8882216363779200, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19800 + ... + 22919.

It is an arithmetic number, because the mean of its divisors is an integer number (3364200).

Almost surely, 2^66641640 is an apocalyptic number.

66641640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

66641640 is an abundant number, since it is smaller than the sum of its proper divisors (148667160).

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

66641640 is a wasteful number, since it uses less digits than its factorization.

66641640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42746 (or 42742 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 33.

The square root of 66641640 is about 8163.4331013367. The cubic root of 66641640 is about 405.4293876071.

The spelling of 66641640 in words is "sixty-six million, six hundred forty-one thousand, six hundred forty".