66887859981 has 16 divisors (see below), whose sum is σ = 89880373440. Its totient is φ = 44243746560.

The previous prime is 66887859971. The next prime is 66887860003. The reversal of 66887859981 is 18995878866.

It is a happy number.

It is not a de Polignac number, because 66887859981 - 2¹⁰ = 66887858957 is a prime.

It is a super-2 number, since 2×66887859981² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66887859971) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3002821 + ... + 3025013.

It is an arithmetic number, because the mean of its divisors is an integer number (5617523340).

Almost surely, 2^66887859981 is an apocalyptic number.

It is an amenable number.

66887859981 is a deficient number, since it is larger than the sum of its proper divisors (22992513459).

66887859981 is a wasteful number, since it uses less digits than its factorization.

66887859981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29996.

The product of its digits is 418037760, while the sum is 75.

The spelling of 66887859981 in words is "sixty-six billion, eight hundred eighty-seven million, eight hundred fifty-nine thousand, nine hundred eighty-one".