66523681 has 8 divisors (see below), whose sum is σ = 76725440. Its totient is φ = 56496528.

The previous prime is 66523657. The next prime is 66523687. The reversal of 66523681 is 18632566.

66523681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 66523681 - 2⁵ = 66523649 is a prime.

It is a super-2 number, since 2×66523681² = 8850800267579522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 66523681.

It is not an unprimeable number, because it can be changed into a prime (66523687) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 42831 + ... + 44356.

It is an arithmetic number, because the mean of its divisors is an integer number (9590680).

Almost surely, 2^66523681 is an apocalyptic number.

It is an amenable number.

66523681 is a deficient number, since it is larger than the sum of its proper divisors (10201759).

66523681 is a wasteful number, since it uses less digits than its factorization.

66523681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87303.

The product of its digits is 51840, while the sum is 37.

The square root of 66523681 is about 8156.2050611789. The cubic root of 66523681 is about 405.1900363052.

The spelling of 66523681 in words is "sixty-six million, five hundred twenty-three thousand, six hundred eighty-one".