63666681 has 8 divisors (see below), whose sum is σ = 91418880. Its totient is φ = 39179472.

The previous prime is 63666679. The next prime is 63666697. The reversal of 63666681 is 18666636.

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

It is not a de Polignac number, because 63666681 - 2¹ = 63666679 is a prime.

It is a super-3 number, since 3×63666681³ (a number of 24 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not an unprimeable number, because it can be changed into a prime (63666601) 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, 816201 + ... + 816278.

It is an arithmetic number, because the mean of its divisors is an integer number (11427360).

Almost surely, 2^63666681 is an apocalyptic number.

It is an amenable number.

63666681 is a deficient number, since it is larger than the sum of its proper divisors (27752199).

63666681 is a wasteful number, since it uses less digits than its factorization.

63666681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1632495.

The product of its digits is 186624, while the sum is 42.

The square root of 63666681 is about 7979.1403672326. The cubic root of 63666681 is about 399.3043763874.

The spelling of 63666681 in words is "sixty-three million, six hundred sixty-six thousand, six hundred eighty-one".