66597681 has 8 divisors (see below), whose sum is σ = 90013600. Its totient is φ = 43790112.

The previous prime is 66597677. The next prime is 66597697. The reversal of 66597681 is 18679566.

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

It is not a de Polignac number, because 66597681 - 2² = 66597677 is a prime.

It is a super-2 number, since 2×66597681² = 8870502229155522, 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 66597681.

It is not an unprimeable number, because it can be changed into a prime (66597611) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 151831 + ... + 152268.

It is an arithmetic number, because the mean of its divisors is an integer number (11251700).

Almost surely, 2^66597681 is an apocalyptic number.

It is an amenable number.

66597681 is a deficient number, since it is larger than the sum of its proper divisors (23415919).

66597681 is a wasteful number, since it uses less digits than its factorization.

66597681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 304175.

The product of its digits is 544320, while the sum is 48.

The square root of 66597681 is about 8160.7402237787. The cubic root of 66597681 is about 405.3402231818.

It can be divided in two parts, 665 and 97681, that added together give a triangular number (98346 = T₄₄₃).

The spelling of 66597681 in words is "sixty-six million, five hundred ninety-seven thousand, six hundred eighty-one".